Trump made another not-so-veiled threat against North Korea yesterday:

Speaking at a news conference with Australian Prime Minister Malcolm Turnbull, Trump made apparent reference to military options his administration has repeatedly said remain on the table.

“If the sanctions don’t work, we’ll have to go phase two,” Trump said. “Phase two may be a very rough thing, may be very, very unfortunate for the world. But hopefully the sanctions will work.”

We have no reason to expect sanctions to “work,” because sanctions usually don’t work and because it is now extremely unlikely that North Korea will agree to denuclearization under any circumstances. Referring to a “phase two” that is “very rough” and “very unfortunate for the world” is an obvious threat to attack, and that is how it will be received. That will just convince the North Korean leadership that it must never give up its nuclear weapons and missiles, and it will encourage them to continue developing both as quickly as possible.

The Trump administration persists in using punitive measures and threats, but these are the very things that have consistently failed to change North Korean behavior for the better and have usually pushed them in the direction that Washington doesn’t want them to go. At the same, they rule out the one thing–real diplomatic engagement–that has produced significant positive results in the past. When the Bush administration blew up the Agreed Framework, they sabotaged the one thing that had been at least partly successful in getting North Korea to limit its nuclear program. Ever since then, North Korea’s nuclear weapons and missile programs have steadily advanced amid international condemnation, sanctions, and threats of attack. We already know that the “maximum pressure” campaign will fail because it is simply intensifying a punitive approach that has been repeatedly tried and found wanting.

When sanctions fail again (and we should take for granted that they will), the U.S. has to pursue diplomatic engagement seriously and it needs to change the goal of its policy. Denuclearization isn’t happening, and demanding it kills any chance of making progress in getting North Korea to agree to limits on its arsenal and its testing. Threatening to use force is folly, and actually using force in this case is insane. If the U.S. is to have any success in negotiating with North Korea, it needs to shelve all proposals for a military attack and it has to be willing to accept a compromise on this issue. Otherwise, the U.S. is headed down a very dangerous path to starting a war that isn’t necessary and could be easily avoided.