The United States has been remarkably successful at preventing the spread of nuclear weapons, but there are new reasons to question whether this track record will last into the future.

Working with partners, the United States has steadily built a framework of disincentives and barriers to prevent proliferation. These include: (1) international treaties and agreements that have erected legal, political, and normative barriers to the bomb; (2) U.S. security commitments to allies that dampen their own need for nuclear weapons; and (3) a set of tough penalties (e.g., sanctions) for those who get caught trying to build the bomb. In other words, the barriers to entry to the nuclear club are high, and those countries that want the ultimate weapon need to be willing to accept significant risks. This helps explain why, although many countries have explored or pursued nuclear weapons, only nine states have them today.

But several trends are eroding the foundation on which this formidable set of barriers rests. These trends are rooted in, and being shaped by, changes to the nature and structure of the international system: namely, the decline of U.S. influence and its gradual withdrawal from the international order that it helped create and lead for more than 70 years, and the concurrent rise of a more competitive security environment, particularly among great powers. These trends (detailed in the report) will have three broad implications for proliferation and U.S. policy. First, they stand to increase pressures on countries to seek nuclear weapons or related capabilities as a hedge. Second, they will almost certainly challenge the United States’ ability to effectively wield the traditional “carrots and sticks” of nonproliferation and counterproliferation policy and dilute the effectiveness of those tools. Finally, they could increasingly pit U.S. nonproliferation goals against other policy objectives, forcing harder tradeoffs.

U.S. policy must adapt unless the United States wants to be faced with a more nuclear-capable landscape in the future.

Read the full report.

This research was made possible with the support of the MacArthur Foundation.