The simulated conflict ended without regime change in Pyongyang, allowing Kim Jong Un to claim a political victory. While avoiding nuclear escalation may seem prudent, such an outcome could deal a lasting blow to the credibility of America’s extended deterrence in East Asia.

The Guardian Tiger scenario should not be dismissed as an academic exercise. It reveals a critical vulnerability in the psychological foundation of deterrence: the perception among adversaries and allies of American willingness to use nuclear weapons in defense of its partners. If allies conclude that Washington will not cross the nuclear threshold even after a nuclear attack, they may question the value of the nuclear umbrella. Adversaries, meanwhile, may learn that nuclear coercion, carefully calibrated, can succeed.

In the simulation, North Korea escalated to a tactical nuclear strike against a South Korean Navy destroyer in the East Sea (Guardian Tiger I) and later against the Chinhae naval base (Guardian Tiger II), home to the Republic of Korea Navy’s Submarine Force Command and occasionally used for allied submarine visits. According to the report, American leaders debated nuclear retaliation but settled on conventional “pulsed” strikes.

In a real-world scenario, such strikes could plausibly involve precision-guided munitions from long-range bombers like the B1-B and Tomahawk cruise missiles launched from Arleigh Burke-class destroyers, aimed at targets such as missile transporter-erector launchers, hardened artillery positions along the DMZ, and command-and-control facilities near Pyongyang. In the exercise, the US stopped short of regime change, seeking to avoid further nuclear escalation and prevent a direct war with China—a decision that would have allowed Pyongyang to absorb the damage, count the survival of its regime as a strategic win, and enter negotiations from a stronger position.

Extended deterrence depends on more than military capability. It is rooted in the belief, shared by allies and adversaries alike, that the United States is willing to defend its partners by all means necessary, including nuclear weapons. An American failure to respond in kind to North Korean nuclear use would plant seeds of doubt. Japanese and South Korean leaders could begin to question whether Washington would truly “trade Los Angeles for Tokyo or Seoul” if the stakes involved limited nuclear use rather than an existential threat to the United States.

That doubt could trigger cascading effects. Calls in Seoul’s National Assembly for indigenous nuclear weapons, expanded production of the Hyunmoo‑4 ballistic missile, and pressure on Tokyo to more seriously pursue nuclear sharing arrangements have already entered the political debate.

This concern is amplified by North Korea’s 2022 nuclear weapons law, which openly authorizes preemptive nuclear strikes in scenarios ranging from an imminent attack on leadership to undefined overwhelming crisis situations. Analysts note that the law’s language effectively lowers the threshold for nuclear use, implying tactical employment to repel invasion and seize the initiative in war. Rather than viewing nuclear use as a desperate last resort, Pyongyang now appears willing to employ such weapons early. For example, a low‑yield detonation against South Korean or American forward-deployed forces to shock Washington and Seoul into political concessions.

The challenge grows sharper in the event of a dual contingency: simultaneous crises on the Korean Peninsula and in the Taiwan Strait. Guardian Tiger II simulated such a scenario, with China launching a multi-domain assault on Taiwan while North Korea escalated on the peninsula. In such a real-world situation, US Indo-Pacific Command could be forced to divert the USS Ronald Reagan Carrier Strike Group from Yokosuka to the waters east of Taiwan, deploy B‑52H bombers to deter Chinese operations, and even consider repositioning some Terminal High Altitude Area Defense and Patriot missile defense batteries from South Korea to protect American assets in Okinawa and Guam.

Such shifts illustrate how a stretched American posture could reduce missile interception capacity on the peninsula and temporarily remove some nuclear-capable platforms from immediate Korean defense. North Korea could calculate that Washington, already balancing a larger confrontation with China, would avoid nuclear escalation in Korea to conserve resources and limit the risk of an all-out US-China war.

The political and strategic consequences would ripple across the region. In Seoul, public and elite opinion could shift sharply toward developing an independent nuclear arsenal—something 71 percent of South Koreans already support. South Korea’s nuclear latency, widely assessed by proliferation experts, suggests it could potentially produce a weapon in as little as 6 months if political consensus formed.

In Tokyo, the debate over counterstrike capabilities, missile defense expansion, and potential nuclear sharing with the United States would intensify, potentially accelerating deployment of Tomahawk missiles and further integration of F‑35A fighters, which, in the US fleet, are being certified for B61‑12 nuclear bombs, into allied defense planning. Beijing, meanwhile, could seize the opportunity to position itself as a stabilizing broker, offering to mediate between Seoul and Pyongyang while shielding the latter from full international accountability, further eroding American influence.

Avoiding nuclear escalation in a limited-strike scenario is understandable, but Washington cannot afford such a decision to be interpreted as weakness. Strengthening deterrence credibility in Northeast Asia will require more than declaratory statements. Clear and credible red lines for nuclear use must be communicated both publicly and privately. Integrated nuclear-conventional planning with allies should ensure that flexible response options, from proportionate nuclear strikes to overwhelming conventional retaliation, are executable on short notice. Contingency planning must explicitly account for simultaneous conflicts in Korea and Taiwan, with pre-positioned munitions, dispersed basing arrangements for nuclear-capable aircraft, and rotational deployments of dual-capable ships and submarines to maintain strategic presence even under force diversion.

Equally important is sustained alliance signaling. These include high-visibility joint exercises like the US-ROK Freedom Shield exercises, regular port visits by nuclear-capable submarines, and trilateral missile tracking drills with Japan. These measures reassure allies, complicate adversary calculations, and demonstrate that any nuclear use will incur unacceptable costs.

The Guardian Tiger exercises are valuable not because they predict the future, but because they reveal how quickly deterrence can fray in the fog of crisis. A single decision to refrain from nuclear retaliation, however understandable at the time, could reverberate for decades and reshape the strategic balance in East Asia. In the nuclear age, preserving deterrence means guarding against both uncontrolled escalation and the perceptions of hesitation that could invite it.

Dr. Ju Hyung Kim, President of the Security Management Institute, a defense think tank affiliated with the South Korean National Assembly, is currently adapting his doctoral dissertation, “Japan’s Security Contribution to South Korea, 1950 to 2023,” into a book.

A Nuclear Umbrella in Peril: Lessons from North Korea’s Escalation Scenarios was originally published on Global Security Review.

Since January 20, Trump administration officials have announced an end to US participation in NATO military exercises; floated plans to relinquish NATO’s Supreme Allied Commander post (held by an American since NATO’s founding); proposed withdrawing 10,000 troops from Eastern Europe; threatened the sovereignty of NATO ally Canada; raised the prospect of using force to seize Greenland (a territory of NATO ally Denmark); derided “freeloading” Europeans; said of Vladimir Putin that America “should take him at his word”; torpedoed NATO’s unanimous declaration to “never recognize Russia’s illegal annexations of Ukrainian territory, including Crimea”; and suggested America’s NATO allies would not “come and protect us” in a time of crisis. This follows Trump’s 2024 invitation to Putin’s henchmen to “do whatever the hell they want” to allies failing to meet NATO’s defense-spending requirements; 2018 threat to withdraw from NATO; and a 2016 declaration that he would defend NATO members under attack only if they had “fulfilled their obligations to us.” Add it all up, and Trump’s view of NATO diverges dramatically from that of what was once known as the “Grand Old Party.”

For instance, as he took the reins as NATO’s first military commander, General Dwight Eisenhower—a future Republican president—called NATO “the last remaining chance for the survival of Western civilization.” President Richard Nixon viewed NATO as “a moral force.” President Gerald Ford believed NATO “protected the free world from the threat of aggression.”

President George H. W. Bush called NATO “an insurance policy.” Indeed, for America, NATO insures against the worst scenario: another European conflict triggering another global war. For the rest of NATO, the alliance is a security guarantee backed by the United States. Without that guarantee, there is no security in Europe, as history has a way of reminding those on the outside looking in, from Cold War Hungary to post–Cold War Ukraine.

President George W. Bush called NATO “the essential foundation of transatlantic security.” This essay did not forget President Ronald Reagan. However, many of those who claim Reagan’s mantle forget that he was an unwavering NATO advocate—during and after the Cold War. Rather than dismissing NATO as “obsolete,” Reagan called NATO “the core of America’s foreign policy and of America’s own security.” Rather than alarming NATO allies, Reagan reassured them by echoing the words of the North Atlantic Treaty: “If you are threatened, we’re threatened…. An attack on you is an attack on us.”

Rather than distorting NATO into a transactional protection racket, Reagan championed NATO as a “community of democratic states” and “a bond which has served us so well.”

Reagan never questioned NATO’s relevance, never browbeat NATO laggards, never threatened withdrawing from NATO, and never raised doubts about America’s commitment to NATO. Instead, Reagan championed NATO as “an antidote to chaos,” “a living commitment of the nations of the West to the defense of democracy and individual liberty.”

Importantly, Reagan did not think NATO’s mission was over when the Berlin Wall fell. In fact, he endorsed NATO’s continued growth. “Room must be made in NATO for the democracies of Central and Eastern Europe,” he declared after the Cold War thawed. And even after Moscow began walking the path of reform, Reagan cautioned, “We cannot afford to forget that we are dealing with a political system, a political culture and a political history going back many decades, even centuries…. We must stick with the strategy of strength.” In short, Reagan shrewdly saw NATO as a hedge against a Russia that might revert to revanchism—which is exactly what has happened.

Putin’s Russia violated nuclear treaties, conventional-weapons treaties, and its own pledge to “respect the independence…sovereignty and existing borders of Ukraine”; warned NATO member Poland that its western territories were “a gift from Stalin”; dismembered NATO aspirants Georgia and Ukraine; countenanced and/or conducted cyberattacks against American energy infrastructure; interfered in elections throughout NATO’s membership roster; conducted sabotage operations across NATO’s footprint (including American targets); threatened use of nuclear weapons; aided and funded attacks against American forces; provided targeting data to support Houthi attacks against allied ships; and made “massive investments in its defense sector” (according to Trump’s own intelligence officials). In light of all of that—and the Kremlin’s long history of deceit—Reagan would never “take Putin at his word.”

GOP presidents, and their democrat counterparts, supported NATO because they recognized that NATO serves America’s interests. For 40 years, NATO helped deter Moscow and prevent the Cold War from turning hot. But that is just a fraction of how NATO has served America’s interests.

Thirteen current NATO allies deployed troops to assist America in defending South Korea. NATO militaries, infrastructure, and decades of interoperability served as the nucleus for the coalition that ejected Iraq from Kuwait, with NATO allies deploying thousands of troops to assist America.

The only time NATO’s all-for-one collective-defense clause was invoked was after September 11, 2001, when NATO allies rushed aircraft and personnel to this side of the Atlantic to guard America’s skies. NATO then bled with America in the Sisyphean campaign that followed, with 455 Brits, 158 Canadians, 86 French, 54 Germans, 48 Italians, 43 Danes, and 40 Poles dying in Afghanistan. When America withdrew from Afghanistan—20 years after the attacks on America’s capital, America’s military headquarters, America’s largest city—74 percent of the foreign troops deployed in the country that spawned 9/11 were not Americans. The vast majority were NATO allies. Trump is apparently unaware of this history.

In Operation Iraqi Freedom, 16 NATO allies sent troops when America asked for help. Hundreds of NATO troops—Brits, Italians, Poles, Bulgarians, Latvians, Danes, Dutch, Romanians, Hungarians, Czechs—died in Iraq, as did 18 soldiers from Ukraine, a country that is not a NATO ally but certainly acts like one.

In the post Iraqi freedom years, seven NATO members conducted airstrikes against the ISIS caliphate. Again, NATO was there.

Far from “freeloading,” NATO allies Britain, Canada, France, Italy, the Netherlands, Norway, and Spain are supporting operations in the Red Sea. Likewise, British, French, Italian, Spanish, and Canadian assets are promoting freedom of navigation in the Indo-Pacific.

European nations sent more aid to Ukraine than the US. Britain and France are organizing a peacekeeping force for postwar Ukraine.

NATO has eight battlegroups defending its most at-risk members along the eastern flank. Only one is American-led.

Britain leads the battlegroup in Estonia, supported by Denmark, France, and Iceland. Britain is committing resources to defend NATO’s northern flank. And the aircraft carrier HMS Prince of Wales just commenced a globe-spanning mission—the largest deployment of British naval airpower in a quarter-century.

Germany leads the battlegroup in Lithuania, backed by Belgium, Czechia, Iceland, Luxembourg, the Netherlands, and Norway. Germany is building permanent bases in Lithuania for 4,800 German troops. Germany is spearheading a continentwide missile shield. And Germany’s parliament recently approved a massive defense-infrastructure fund.

Canada leads the battlegroup in Latvia, supported by 10 other NATO allies. France leads NATO’s battlegroup in Romania. Pouring almost 5 percent of GDP into defense, Poland fields NATO’s third-largest military. Sweden is quadrupling production of anti-tank weapons.

What NATO is doing and deterring underscores something General James Mattis observed almost a decade ago, “If we did not have NATO today, we would need to create it.”

This begs the questions: what if we did not have NATO? What if these first hundred days mark the last days of history’s greatest alliance for peace?

NATO is designed not to wage war, but to deter war. If there is any doubt about NATO’s collective-defense guarantee—and these first hundred days have created enormous doubts—Putin could be tempted to do in the Baltics what he has done in Ukraine. That would force NATO to blink or fire back. And that would lead to terrible outcomes. The former means the collapse of NATO—and with it, the entire US-led alliance system. The latter means great power war.

The best way to prevent such dire outcomes is through deterrent military strength, clarity of intent, and certainty of cause and effect. Trump’s words and actions have undermined all of these.

What the transactional Trump administration fails to recognize is that by undermining NATO, it is undermining America’s security. If a cyberattack or EMP blast or bioweapon paralyzes America; if ISIS or al Qaeda or some other terror group unleashes something worse than 9/11 or 10/7; if Moscow blinds America’s constellation of satellites; if Beijing moves against Taiwan; or if Pyongyang restarts the long-paused Korean War, America will call for help.

A post-NATO Europe may be unable or unwilling to answer.

Alan Dowd leads the Sagamore Institute Center for America’s Purpose.

FYI to the GOP on NATO was originally published on Global Security Review.

Indeed, as of this writing such probes are already occurring. Sino-Russian aerial probes against Alaska recently occurred in the Arctic. While American officials claim this is the first time this happened, Chinese officials stated that this is the eighth such joint aerial probe. Moreover, the probe took place immediately following Sino-Russian bilateral naval exercises in the South China Sea and around Taiwan.

In a similar fashion, there is evidence that China is providing missile technology to North Korea. This follows the new mutual security pact signed by North Korea and Russia, which came after North Korea made itself a supplier of missiles to Russia in its war against Ukraine. Russian assistance to North Korea’s satellite program is also reportedly taking place.

In the Middle East, China’s negotiation of an agreement on Hamas-Palestinian Authority unity not only conforms to long-standing Russian objectives, but it also facilitates further Sino-Russo-Iranian influence among Palestinians—making a durable Middle East peace even less likely. Pyongyang’s willingness to proliferate nuclear and missile technology to Iran and a de facto Russo-Iranian alliance, only further destabilizes the region and makes a larger scale war more likely.

The same is true in Europe where China emerged as the primary source of Russian revenues, defense technologies, and diplomatic support for its war on Ukraine. Without Chinese support, Russia would be hard-pressed to continue the war. At the same time, numerous accounts show that Russia is engaged in cyber war against Europe, attacking infrastructure and cyber networks. Russia is also planning assassinations of key figures and other mayhem within the countries of the North Atlantic Treaty Organization. Russia is not alone in engaging in these behaviors. While the attacks on France’s national railway system on the eve of the Olympics was very likely a Russian plot, Iran is concurrently threatening Israeli athletes at the Olympic games through cyberattacks.

The number of global attacks and coordination among these four actors, all of whom use nuclear weapons to deter the West from responding to their gray zone attacks, is increasing. Once Iran fields its own nuclear arsenal, which seems increasingly likely, more terror campaigns against Israel, other Middle East states, and international shipping (by Iranian proxies) is likely.  Indeed, the Houthis granted safe passage to Chinese and Russian ships in the Red Sea while Moscow is considering giving them anti-ship missiles. These facts also raise the issue of their use of cyber and hacking devices, if not GPS, to direct and track ships in the Red Sea.

Accordingly, the West faces a multi-domain threat linking all the domains of warfare, including nuclear escalation. These autocracies already incorporated nuclear deterrence, if not escalation, into their strategies against the US and its allies in Asia, Europe, and the Middle East.  North Korea, as well as China and Russia, is building a larger and more diversified arsenal. Soon, North Korea will field a nuclear triad of fighter-bombers, intercontinental ballistic missiles, and submarine-launched cruise missiles.

As a result of their policies, there is virtually no hope of arms control in the near future. China’s recent walkout from nuclear talks exemplifies the utter impossibility of arranging arms control with either Beijing or Moscow. By the same token nonproliferation and the nonproliferation treaty are evidently on their last legs. Beijing’s announcement of its commitment to that treaty’s renewed credibility is thus a grim joke given its ongoing record of support for proliferation. For the next administration, which must deal with facts rather than wish-fulfillment in its defense policy, it is clear that a sustained program of conventional and nuclear modernization, if not an actual increase, is necessary. Moreover, nuclear proliferation appears increasingly likely.

If Iran goes nuclear, the pressure on Saudi Arabia to follow suit increases exponentially. Egypt and Turkey may also follow suit, leading to a Middle East that is equally unstable, but with more nuclear powers.

South Korean public opinion is apparently increasingly supportive of an independent nuclear arsenal, which would lead Japan to follow suit. In short, China, Iran, North Korea, and Russia are all making the world a less safe place as they challenge world order.

While Americans already live in interesting times, the times are likely to become even more interesting as they become more threatening. The United States will face a nuclear-armed autocratic quartet that is focused on supplanting American power. That quartet is also likely to be more dangerous than ever before because the threat, if not the actual use of nuclear weapons, offsets their conventional inferiority and increases their war-making power.

The fevered rhetoric of the current presidential campaign will soon end. The intractable realities will neither end nor give the next administration any respite. They will challenge the nation and force Americans to turn their inward gaze outward.

Steve Blank, PhD, is a Senior Fellow at the National Institute for Deterrence Studies. The views expressed are his own.

The New Nuclear Alliance Against the West was originally published on Global Security Review.