The retrospectives and forecasts about 9/11 keep on coming, but little has been written about that day’s impact on the Bomb, arms control, and new nuclear weapon programs. Here’s my take, subject to rebuttals:

1. The most important and obvious repercussion has been the shift in focus from nuclear threats posed by major powers to those from weakened states and messianic militants. Russian and Chinese authorities are capable of bucking this trend with extremely unwise, revanchist choices: a new liquid-fueled, ten warhead, land-based missile in Russia and a new-found enthusiasm for using nuclear threats to supplement economic leverage in China come to mind. But it would take very jarring steps to reverse current trends, preceded and reinforced by the events on 9/11, that nuclear weapons have become progressively less useful for major powers, even as their utility has grown for troubled, weakened regimes.

2. The absence of acts of nuclear terrorism by means of “dirty” bombs, improvised nuclear devices or warheads from an existing arsenal is the best surprise of the ten years following 9/11. Stretch this record back to the demise of the Soviet Union and this result is even more astonishing and perplexing. An act of nuclear terrorism or a mushroom cloud could still occur tomorrow, but there has been twenty years of tomorrows since the Soviet Union collapsed, opening a Pandora’s box filled with the worst substances created by man. The absence of catastrophic WMD terrorism thus far speaks volumes about the wisdom of the Nunn-Lugar program in the former Soviet Union, the extension of cooperative threat reduction programs to other countries, the regrettable ease with which mass casualties can be produced with readily available explosives and automatic weapons, much improved intelligence efforts, good fortune, and inflated threat assessments. Maintaining a track record of non-use of WMD will be a challenge over the next decade if complacency sets in, budgets are trimmed, and if the number of outlier states grow.

3. The events of 9/11 greatly weakened the ability of the U.S. nuclear weapon labs to generate support for new warhead designs. This extraordinary loss of clout was predictable after the demise of the Soviet Union, but was never more evident than after the quick unraveling of the Bush administration’s proposals for bunker-busting, deep penetrating warheads to deal with post-9/11 threats.

4. The events of 9/11 have had little impact on the standoff between those in the United States who love or hate arms control and nuclear weapons. For the foreseeable future, domestic divisions on these issues, as on so many others, will be extremely hard to bridge. This suggests rough sledding ahead (and perhaps tradeoffs) for those in the United States who seek treaty ratifications and strategic modernization programs.

5. The events of 9/11 have clarified the utility of more creative and less formal approaches to nuclear threat reduction, including norm setting by means of codes of conduct and political compacts by like-minded states, such as the Proliferation Security Initiative. Newer approaches have been constructed atop the load-bearing walls built by treaties. Continued efforts by anti-arms controllers to demolish treaties will therefore further damage their own adaptive creations.

6. There have been notable successes in the field, well beyond the avoidance of catastrophe, in the ten years since the 9/11 attacks. Two regimes with WMD ambitions – those led by Saddam Hussein and Muammar Qaddafi – are gone. The Assad franchise in Syria is wobbly. According to SIPRI’s calculations, global stockpiles of nuclear weapons have been reduced by 16,000 over this ten-year period, along with 12,000 fewer deployed warheads. No major powers have tested nuclear devices during this decade. The NPT has been reaffirmed. A ten-year long verifiable treaty governing further strategic arms reductions between Moscow and Washington is in place, providing time and space for negotiators to tackle far more complex issues. Nuclear security now receives summit-level attention.

7. And now for the flip side: successes have come with significant costs, beginning with two wars that are more likely to have murky, indeterminate or negative outcomes than positive ones. Iran and North Korea have been unintended beneficiaries of the wars in Afghanistan and Iraq, having gained freedom of maneuver while Washington lost capacity to influence their nuclear choices. Ten years after 9/11, divisions within the United States have grown markedly, even at a time of engagement in foreign wars. Divisions are also growing internationally between nuclear haves and have-nots. The Board of Governors at the IAEA is more politicized and the Nuclear Suppliers Group is weaker now than ten years ago. Successful arms control, nonproliferation and disarmament have always depended upon consensual approaches, but consensus has become a more elusive commodity in the decade following 9/11.

8. My bottom line: the new normal for this field is concurrent good and bad news. There has been progress on some important fronts since 9/11, but game changers are more likely to be negative than positive. As John McPhee wrote in The Control of Nature (1989) on the subject of the successful defense of Vestmannaeyjar, Iceland against an advancing lava flow,

The true extent of the victory will never be known – the role of luck being unassessable, the effects of intervention being ultimately incalculable, and the assertion that people can stop a volcano being hubris enough to provoke a new eruption.

Victories in arms control, nonproliferation and disarmament are rarely decisive. But disaster has so far been avoided. There are good reasons for momentary – and only momentary — satisfaction.