Concealed nuclear weapons: an atomic-age nightmare that's never gone away

Finished another feature for Air&Space/Smithsonian Magazine, "Block that Bomb," online today and linked here. It describes a major, and majorly secret, effort to use disguised gamma- and neutron-detection gear at American airports and seaports to catch Soviet agents trying to smuggle nuclear weapon components into the US, perhaps concealed in diplomatic "pouches." It predated by almost two decades the well-known passenger screening that began after a string of airliner hijackings. 

War-gamers of the Pentagon figured that the Soviets might plant a few big ones in New York and Washington and set them off moments before their bombers appeared on our radar net. Detection-equipment work started late in the Truman Administration, inspired by this Soviet test in August 1949:

Over the decades, the main effort shifted to overseas detection work (such as the "loose nukes" problem), and away from reliance on catching all inbound weapons-grade uranium and plutonium at the US border. 

I note in the article that public concern today about an adversary's concealed nuclear weapon is much less than in the Fifties (which saw a string of potboiler thrillers on the topic, like The 49th Man), but the risk could be higher. During the early years, if a bomb were found the only possible suspect would have been the USSR since only the US and USSR had any; and that posed a risk of an immediate retaliatory strike.  

As the number of nuclear states and non-state terror groups has grown, attribution of who is behind a particular nuclear sneak attack will be much more difficult. That suggests that the risk of one country starting a war by setting off a bomb to disable the enemy's seat of government or military HQ (sometimes called a decapitation strike) is higher. 

After the article I checked with friends who live in the DC area and asked what they knew about evacuation drills, and whether they had checked into how to leave the city quickly if an alert were sounded. They had some suggestions on ways to leave without getting stuck in traffic panics, as happened on 9/11 and during several false alarms later. And the city has tested mass-evacuation and nuclear-response plans over the years. If there's interest I'll post on that.