It was not until June 6, 1944, four years later, that the allies landed on the Normandy coast. Over 200,000 troops, in a 48-hour period, in the largest amphibious operation in history, stormed the beaches to do what the Germans thought impossible. Eight months later, Germany was defeated.

The cost was high, however. With the German Army facing little opposition in the Rhineland, Austria, or Czechoslovakia, the German invasion West into the low countries and France was easy. Western Europe fell in a matter of three months from April to June 1940. At the end of the day, once deterrence was lost, World War II led to the death of over 60 million people. Getting deterrence back was a tough proposition.

In 1949, the United States withdrew its military from the Republic of Korea. Then, in January 1950, the US Secretary of State, Dean Acheson, asserted that the Republic of Korea (ROK) was beyond the US defense perimeter. In early June, the US Congress approved an aid package for the ROK, but it was not delivered until after the North Korean invasion that began on June 25, 1950. Undermining American deterrence of North Korea with Acheson’s speech ultimately cost 2 million Korean lives and nearly 200,000 allied casualties.

Although the US was able to reestablish deterrence in Korea seven decades later, in 2014, the United States lost effective deterrence once again—this time in Europe. That was the year Washington declared that Ukraine was not of interest to the United States, leaving Ukraine to the tender mercies of the Russian Army. Russia soon took Crimea and ultimately launched a brutal invasion in 2022.

In 2021, the US withdrew ignobly from Afghanistan, further signaling the nation’s enemies that the US was not in the deterrence business. The consequences of that act are still unknown.

Later in 2021, the administration hesitated in making it clear whether Washington would or would not defend Ukraine from further Russian aggression. Though the mistake was later rectified, the damage to deterrence was done.

Further harm came to Ukraine, the US, and the North Atlantic Treaty Organization’s (NATO) European member states when it became clear Washington was fearful of a Russian escalation of the conflict should the allies get serious about pushing back against Russian aggression. Russian President Vladimir Putin repeatedly threatened the use of nuclear weapons should Ukraine and the allied coalition get serious about rolling back Russia’s aggression—the successful use of Russian deterrence.

To counter the American loss of deterrence, Congress agreed to markedly increase defense spending and investments in America’s nuclear deterrent, space capability, and missile defense. Over time, and coupled with a sense of urgency, the United States can restore deterrence if these new investments are sustained.

The nation’s legacy nuclear deterrent, which is now between 35 to 65 years old, will soon age to obsolescence. The Sentinel intercontinental ballistic missile (ICBM), Columbia-class ballistic missile submarine (SSBN), and the B21 Raider strategic bomber, along with the long-range nuclear cruise missile, once built, will markedly restore nuclear deterrence. An improved theater nuclear deterrent, with a new sea-launched nuclear cruise missile and a stand-off nuclear capability for the F-35, would also significantly improve deterrence.

These systems give the nation the capability required to deter China and Russia. However, the second part of deterrence is will. Whether the United States has the will to employ its deterrent capability is uncertain.

How the administration handles Iran will say a great deal about how adversaries see American will. The administration is committed to preventing Iran from getting a nuclear weapon. Washington said you could do this the easy way or the hard way. A negotiated deal is one way but military strikes on Iran’s nuclear infrastructure is the other.

With the Israelis and Americans on the same page and the war already begun, the die is now cast and the US does not have endless patience. But whether it is willing to use military force is uncertain. Although Henry Kissinger once said that diplomacy without the threat of force is without effect, the conventional wisdom in Washington is that no military action will be forthcoming.

The Trump administration carefully laid out a challenge to the Iranians. There were 60 days for negotiations. Now, it is widely known that on day 61 the Israelis, with US missile and air defense assistance, took out most of the above ground Iranian nuclear capability as well as the top Iranian nuclear leadership.

Perhaps Israeli deterrence credibility was restored, but whether that is true of the United States is far less certain. The Trump administration did what it said it would do. The Israelis did what they had to do. Both nations did what was necessary to restore deterrence. The Iranian nuclear capability is gone. How this will affect Chinese and Russian aggression, that requires more insight.

Peter Huessy is a Senior Fellow at the National Institute for Deterrence Studies.

Restoring Deterrence was originally published on Global Security Review.