What are tactical nuclear weapons and how might Putin use them?

Russian President Vladimir Putin said this month he's not bluffing about using nuclear weapons. If he were to follow through on that threat, it's likely his weapon of choice would be tactical nuclear weapons. He's also not the only one talking about these weapons. North Korea's recent missile tests involved "tactical nuclear" drills to simulate hitting South Korea, according to the North's state-run media.

What are tactical nuclear weapons?

Tactical nuclear weapons are sometimes referred to as "small nukes," even though they still cause devastating fatalities and destruction. They are designed for limited strikes against relatively close specific targets, like command posts, instead of destroying cities from afar.

The explosive yield of tactical nuclear weapons can range from under one kiloton to about 100 kilotons, whereas strategic nuclear weapons can have a yield up to one thousand kilotons. The bombs that destroyed Hiroshima and Nagasaki in 1945 were between 12 and 21 kilotons. The one dropped on Hiroshima weighed 9,700 pounds and a 10,800-pound bomb leveled Nagasaki.

Tactical nuclear weapons can have a similar yield or greater — up to several times as powerful as the Nagasaki bomb — but they are often smaller and more portable. For instance, during the Cold War, the Soviet Union developed devices small enough to fit into a suitcase-sized container.

Why were tactical nuclear weapons developed, and have they ever been utilized?

No one has ever used a tactical nuclear weapon in combat. Both the U.S. and the Soviet Union developed them early on during the Cold War as a method of deterrence. The NATO allies had them in Europe as part of their "flexible response" strategy to show the Soviet Union and its allies that any conflict, even one with conventional weapons, could have nuclear consequences.

How many deaths could result from a tactical nuke?

There is a wide range. Over 70,000 people are estimated to have died immediately when the U.S. bombed Hiroshima. Thousands of others later died due to poisoning from the radiation.

Tactical nuclear weapons, by design, do not have as much radioactive fallout, since they are used against a specific target, but there is still some fallout.

Nuclear historian Alex Wellerstein has built a simulation called NukeMap to estimate the effects of nuclear strikes. According to NukeMap, if the Davy Crockett, the smallest U.S.nuke ever produced, were to be used on a neighborhood in Washington, D.C., it would kill 3,270 people and injure 3,620. Other tactical nuclear weapons are larger and would result in a more devastating death toll.

How many tactical nuclear weapons are there now?

The most recent public U.S. intelligence estimates estimate Russia has up to 2,000 tactical nuclear weapons in its stockpiles. The U.S., on the other hand, has slightly more than 200.

The U.S. and other western countries decided decades ago to scale down their tactical nuclear weapon inventories because they believed there were more efficient deterrence methods and because of the risk that the small, portable weapons could get into the wrong hands, like terrorists.

How could Putin use a tactical nuclear weapon?

Putin could decide to launch a demonstration strike over the Baltic Sea or Black Sea as a scare tactic — not hitting people or infrastructure but proving capable of using nuclear weapons. Or he could conduct a strike against Ukrainian infrastructure, like a Ukrainian military base.

Russia could deploy a tactical nuclear weapon by ground, air or sea, using missiles that normally carry conventional explosives.

What would Putin gain by using a tactical nuclear weapon?

It's not clear Russia would gain anything from using a tactical nuclear weapon in Ukraine. President Joe Biden told CBS News' "60 Minutes" in September that if Russia were to use a tactical nuclear weapon, "they'll become more of a pariah in the world than they ever have been. And depending on the extent of what they do will determine what response would occur."

The Institute for the Study of War (ISW) said that if Putin decided to use a tactical nuclear weapon, it would likely be because he wants to shock Ukraine into surrendering or cut off western aid. But ISW doubts that such a strike would achieve either of these objectives.

How would the U.S. respond to a tactical nuclear weapon strike?

President Biden said at a private fundraiser this month that the world might face "the prospect of Armageddon" if Putin decided to use nuclear weapons and that the administration is trying to figure out what Putin's "off-ramps" might be so that the situation does not escalate.

National security adviser Jake Sullivan said on "Face the Nation" last month the administration has warned Russia of "catastrophic consequences" if it resorts to using nuclear weapons, but he offered no further specificity.

At this point, the U.S. has not assessed that Putin has made a decision about using a tactical nuclear weapon, Pentagon Press Secretary Brig. Gen. Patrick Ryder said in a press briefing last week.

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