WASHINGTON — When Defense Secretary Jim Mattis declared on Tuesday that North Korea now had the missile capability to “threaten everywhere in the world, basically,” he hinted at a long-running debate inside the United States government: Can the same strategy that worked against the Soviet Union — mutually assured destruction — also work against a far smaller adversary?

The answer is yes, of course it can, if the problem is defined as keeping Pyongyang from unleashing a surprise attack on the continental United States. Or no, it probably can’t, if the problem of containing North Korea is more complex than simply protecting Los Angeles and Washington.

And with North Korea, as the past 70 years of bitter experience have repeatedly shown, almost everything is more complex.

There is no evidence that Kim Jong-un, North Korea’s current leader, or his father or grandfather, ever contemplated getting into a direct nuclear exchange with the United States. Depending on whose estimates one believes, North Korea has 20 to 60 nuclear weapons; the United States has more than 1,500 currently deployed, and thousands more in storage. It would be, as one senior American military strategist put it a few weeks ago, a case of assisted suicide.