The danger of nuclear war in the world just diminished drastically. Americans are safer now than they were. America has a vital interest in preventing the spread of nuclear weapons. By striking Iran, President Trump showed the resolve to use force to uphold that interest. The strategic significance of the blow extends far beyond Iran.

This was the first time the United States used a military attack to stop a country from acquiring a nuclear bomb. In the past, it had opposed nuclear proliferation through diplomatic pressure, economic sanctions, and multilateral agreements. Those means have their merits but also their limitations. To be effective against rogue regimes, they have to be backed by power. President Trump has now made clear that America has that power and will use it to serve its nonproliferation purposes. Many U.S. presidents threatened military force to stop the spread of nuclear weapons, but until now those threats were of doubtful credibility.

This was not, however, the first time Israel used its military against an enemy’s nuclear program. The history is noteworthy. Israel sent its air force to hit Iraq’s Osirak reactor in 1981 and to hit Syria’s nuclear facility in 2007. No major retaliation, let alone a new war, resulted, and neither Iraq nor Syria even tried to revive their nuclear weapons programs. Both decided it was not worthwhile to rebuild, given Israel’s determination to prevent any such program from succeeding.

Trump’s action has produced criticism from the left and also within his political camp. Some MAGA critics have argued that Iran is a distraction from containing China and ending reckless government spending. Those are important priorities, but the spread of nuclear weapons is one of the greatest threats in the world to the security, prosperity, and well-being of Americans. Even by the strictest standards of MAGA restraint in world affairs, the United States has to prevent such proliferation.

If Iran became a nuclear power, the danger would extend beyond aggression, sponsorship of terrorism, and other bad actions by Iran. Iran’s achievement would spur Saudi Arabia, Turkey, Egypt, and other states in the Middle East and beyond to become nuclear powers too. The number of nuclear powers in the world, now fewer than 10, could in short order grow to 20 or 30. This would create greater risks of catastrophic accidents and "dirty" bomb terrorist attacks. If the world had dozens of nuclear powers, the likelihood of nuclear conflict would increase. Even a limited nuclear exchange could produce enormous harm, and not just to the parties involved in the exchange. It could gravely damage Americans by devastating global markets and supply chains, poisoning Earth’s atmosphere, and contaminating agriculture.

The blow struck by Operation Midnight Hammer will reverberate globally. Any country seeking a nuclear bomb—or considering providing one to others—now understands the United States may use force against it. This credible threat will make nonproliferation diplomacy more effective. It will reassure America’s allies that Washington is intent on maintaining the nuclear status quo.

The U.S. attack on Iran’s nuclear facilities is more than a tactical military success. It is a strategic reaffirmation of American global leadership. Nuclear nonproliferation efforts since 1945 have not been a perfect success. But they have been astonishingly effective. They represent one of the most significant achievements of the United States (and key partners) in international security. That fewer than 10 nations possess nuclear weapons today reflects the effectiveness of combined diplomatic, economic, and military pressures. The strike against Iran reinforces the point—critical to the interests of the United States and the world in general—that rogue states pursuing nuclear weapons will face not just disapproving diplomacy and economic sanctions, but maybe also military destruction. It’s a harsh but constructive message.

Douglas J. Feith, a senior fellow at Hudson Institute, served as Under Secretary of Defense for Policy from 2001-05. Dore Feith recently graduated from Columbia Law School.