Which nuclear threats should we worry most about?

During his 24-day reign as national security adviser, Michael Flynn put non-nuclear Iran “on notice” after it conducted a medium-range ballistic missile test in late January. Flynn directed no comparable warning to nuclear North Korea after it conducted a more significant missile test two weeks later. Meanwhile, no one had apparently put Flynn “on notice” about his multiple conversations with the Russian government concerning U.S. sanctions in the wake of Moscow’s interference in the U.S. elections.

Between the internal politics of the Trump White House, the political maneuverings of foreign governments, and the arcane technical details of nuclear missile programs, it is difficult to make sense of it all. But it is important for us to try, because our reactions to this news may make the difference between war and peace.

Of the world’s nine nuclear weapons states, three are potential adversaries; two can destroy our country in short order: Russia and China. If either decided to launch an all-out nuclear attack, there is nothing — including our missile defenses — that could spare us from nuclear annihilation. Fortunately, the Russians and Chinese know that such an attack would result in their own countries being destroyed in response.

North Korea is our only other adversary with nuclear weapons. It is some years away from being able to attack the United States, but it can already contemplate nuclear attacks on U.S. allies or U.S. military forces in the Pacific. Yet its leadership also understands that such an attack would be suicidal.

Nuclear-armed India and Pakistan confront each other across a disputed common border with an imbalance in conventional power. They have waged four wars against each other since gaining independence and have still not achieved a stable relationship. A nuclear war involving these two states alone could kill 20 million people within a week and put some two billion at risk from starvation worldwide.

Other nuclear dangers derive from the large arsenals held by the nine nuclear weapons states. If a terrorist group acquired even a single nuclear device, it would pose a potent threat of blackmail. Nuclear use would be undeterrable and disastrous if detonated in an urban area.

How should these threats be ranked? I hold an India-Pakistan nuclear conflict as being the most likely, with nuclear terrorism a close second. The most dangerous dynamic is the unconstrained nuclear and missile testing of North Korea — partly because it risks provoking a “preventive” first-strike by the United States.

I do not include Iran on this list of potential near-term nuclear horrors. Although Iran may have a hostile government, which abuses human rights and aids terrorists in the region, it is also an enemy to ISIS and al-Qaida — the top terrorist targets of the United States. Most important, it agreed to and is complying with a seven-country nuclear deal, which effectively blocks for 15 years all paths to acquiring the material needed to build a nuclear bomb — and it is not testing long-range ballistic missiles.

Our top goals now should be achieving mutual reductions in the huge Russian and U.S. nuclear arsenals, seeking resolution of the Indian-Pakistani differences aggravating their nuclear arms race, negotiating a freeze on North Korea’s nuclear program, and strengthening safeguards against terrorist acquisition of nuclear material.

During my career, I often noticed how vulnerable the public is to willful manipulation of the facts dealing with foreign threats. I personally witnessed the deliberate distortion of information related to Iraq’s nuclear weapons program prior to our 2003 invasion. I worry today that the Trump administration is paving the way for a war against Iran. The first step off that path is to demand the facts — not “Flynn facts” or “alternative facts,” just the facts.

Greg Thielmann, a native of Newton, is a 25-year veteran of the U.S. Foreign Service, who subsequently served as a Senate Intelligence Committee staffer and as a senior fellow of the Arms Control Association.