The Trump administration has every reason to be exasperated by North Korea’s continued acceleration of its nuclear weapons program, which poses a threat not only to South Korea but also to other countries in Asia and potentially to the United States. But Secretary of State Rex Tillerson went too far during his current swing through Asia by seeming to suggest that the United States might engage in a preemptive military strike against North Korea.

“Certainly we do not want things to get to a military conflict,” Tillerson told reporters in Seoul. But he added that “if North Korea takes actions that threaten the South Korean forces or our own forces, then that will be met with an appropriate response. If they elevate the threat of their weapons program to a level that we believe requires action, that option is on the table.”

There’s nothing new about the idea that the U.S. would defend South Korea against an attack from the North. But Tillerson seemed to be raising the possibility of a pre-emptive strike. If that was his meaning, the threat was premature, because the U.S. has other ways to deter North Korea. But the ambiguity of his words was itself a problem. Its vagueness recalled former National Security Advisor Michael Flynn’s warning earlier this year that he was putting Iran “on notice.”

At the same time, Tillerson seemed to rule out resuming negotiations with the North even if the North agreed that the goal of the talks would be denuclearization. “The policy of strategic patience has ended,” Tillerson said, referring to the Obama administration’s strategy of hoping that economic sanctions would force Pyongyang to resume negotiations.

We don’t fault Tillerson or President Trump for responding to recent North Korean missile tests. The U.S. is installing a missile-defense system in South Korea despite complaints by China that its sophisticated radar would thwart Chinese defenses, and the same system could also be deployed in Japan. Presumably the U.S. is also continuing cyber-attacks against the North Korean nuclear program. Meanwhile, the U.S. continues to urge China to put more pressure on North Korea.

Nor was Trump wrong when he tweeted on Friday that “North Korea is behaving very badly. They have been ‘playing’ the United States for years.” North Korea has made commitments not only to the U.S. but to other nations and then reneged on them, and the U.S. shouldn’t engage it in negotiations until Pyongyang makes it clear that it is serious about giving up nuclear weapons in exchange for security guarantees. But as the U.S. explores what Tillerson calls a “new approach” to North Korea, it should leave open the door to negotiations.

Meanwhile, it’s important that the president and the secretary of State not engage in what sounds like saber-rattling.

—The Los Angeles Times, March 17, 2017