In less than fifteen months as president, Barack Obama has transformed the role of nuclear weapons in American foreign policy. Some observers have criticized Obama for limited progress in the Middle East and other regions. On nuclear weapons, Obama deserves praise for his vision and commitment. He deserves more support at home and abroad.

From the 1950s until the present, nuclear weapons have played a central role in American foreign policy. They were the cornerstone of containing communist advances in Western Europe. The United States threatened to unleash its nuclear arsenal on targets in the Soviet Union if the Kremlin’s forces crossed the “tripwire” separating East and West Germany. By the time of the Berlin and Cuban Missile Crises in 1961 and 1962, the threat of mutually assured destruction convinced leaders in Washington and Moscow to renounce aggressive moves and accept compromise – the beginnings of “détente.” Nuclear weapons deterred aggression in the most dangerous areas of conflict.

Nuclear weapons played an important, although less clear, role in the conflicts over Korea (1950-1953), the Taiwan Strait (1954-55 and 1958), and Vietnam (1954-1975). Presidents from Dwight Eisenhower to Richard Nixon seriously contemplated the use of nuclear weapons against stubborn non-European enemies, but they decided otherwise for a combination of reasons – including the questionable military value of nuclear strikes, international political opposition, and fears of future retaliation. Nuclear weapons raised the risks of destruction in far away conflicts.

One of the great American fears during the Cold War was that these weapons would fall into “irrational” hands. Soviet leaders had proven that they would not jeopardize their own survival through rash acts of violence. Could the same be said for Communist China, in the throws of an internal revolution against “bourgeois” restraints on people power? During the 1960s, American leaders perceived that Mao Zedong might act as a nuclear terrorist, believing his populous country would outlast it better armed adversaries. Mao threatened as much in his infamous bombast that the United States was a “paper tiger.” President Kennedy took Mao seriously, preparing plans for a preventive strike against China. Kennedy also warned that the greatest threat to American security could be the emergence of more than a dozen nuclear states, many as unpredictable as China. American, Soviet, and West European efforts to restrain the emergence of new nuclear states produced the Nuclear Non-Proliferation Treaty of 1968 and other efforts to keep the nuclear club as small as possible.

Nuclear weapons remained vital to American and Soviet foreign policy in the 1970s and 1980s, but few new nuclear states emerged because of pressures from the superpowers. With the end of the Cold War that changed. Countries surrounded by dangerous enemies turned to nuclear weapons for many of the same reasons Washington initially deployed these capabilities – to deter foreign attacks and increase external leverage. India, Pakistan, North Korea, and Iran have real security reasons for going nuclear. They all have a strong argument against efforts to restrain their nuclear programs: if the United States is so strong and yet so committed to deploying nuclear weapons, why shouldn’t smaller, more imperiled countries do the same?

Barack Obama is the first American president to take this argument seriously. Unlike most of his predecessors since the 1950s, Obama recognizes that the United States must diminish its own reliance on nuclear weapons if it wants to curtail the spread of these devices. He also acknowledges that the large American nuclear arsenal has very limited military use against the threats confronting the United States. These insights come from Obama’s long-time study of these issues, dating back to his days as a student of international relations at Columbia University in the early 1980s.

As president, Obama has moved decisively to diminish the American nuclear arsenal and its role in American foreign policy. Just weeks after his inauguration, he traveled to Prague and passionately advocated the ideal of a nuclear-free world. He re-opened arms control negotiations with Russia, and he has completed a ground-breaking treaty with President Medvedev that will reduce Russian-American nuclear arsenals by more than a third. Obama has also issued a Nuclear Posture Review that pledges the United States will use its nuclear arsenal primarily to deter nuclear threats, not conventional, chemical, or even biological dangers. According to this new policy, countries that adhere to the Nuclear Non-Proliferation treaty need no longer fear that the United States will launch its nuclear arsenal against them. This week Obama is hosting a conference of more than forty states in Washington D.C. — the largest such gathering called by an American president since 1945 — to address the global safety and security of nuclear materials.

We are still far from a nuclear-free world. Nuclear threats from states like North Korea remain real. The nightmare of a nuclear terror weapon, in the hands of Al Queda or some other trans-state group, remains serious. The United States and Russia continue to deploy bloated nuclear stockpiles. Newer nuclear states — including China, India, and Pakistan –look like they might be poised to follow this dangerous path.

We have, however, come a long way very quickly. President Obama has shown leadership in turning mainstream politics against the bomb. This is a bright sign of progress in a time of troubles. Leaders really do matter.

The opinions expressed in this blog are personal and do not necessarily reflect the views of either Global Brief or the Glendon School of Public and International Affairs.