WASHINGTON — A day after the U.S. secretary of state warned of military action against North Korea if it does not negotiate to relinquish its nuclear weapons, several U.S. lawmakers exhorted that even limited strikes would provoke a catastrophic war.

Following reports the Trump administration is weighing limited, pre-emptive “bloody nose” attacks to rid Pyongyang of its nuclear program, two Iraq veterans in Congress want the administration to drop the idea — and for President Trump to curb his fiery rhetoric.

Pyongyang, could within hours of being attacked, kill hundreds of thousands of South Koreans and Americans in Seoul and the surrounding areas before allies could suppress North Korea artillery, they said. From there, there would be tens of thousands dead per day, for weeks and months.

“So there’s no such thing as a limited strike, whether or not you use a nuclear cruise missile,” said Illinois Democratic Sen. Tammy Duckworth. “You will have massive, massive noncombatant injuries, casualties, as well as military casualties.”

“A lot of Americans don’t understand that, and I don’t think the president understands that from the way he tweets,” she said.

Duckworth and Arizona Democratic Rep. Ruben Gallego spoke with reporters Wednesday, after their five-day trip to South Korea and Japan, where they met with top military and civilian officials from those countries and U.S. military officials.

U.S. and allied military forces are ready, but the emphasis needs to be on diplomacy and sanctions, they said. “Continuing to move those forward and deescalation of provocative words and acts by President Trump would be helpful, and continued pressure on Russia and China to fully implement our sanctions regime,” Gallego said.

Speaking separately at the conservative American Enterprise Institute, Sen. Lindsey Graham — a South Carolina Republican who golfs with and advises the president — said he was “100 percent confident” Trump would go to war against North Korea as a “last resort.” He cautioned Pyongyang’s quest for a long-range nuclear weapon is making a confrontation ever more likely.

“I know there are some red lines in the president’s’ mind,” said Graham, a retired military lawyer and member of the Senate Armed Services Committee. “I know there are some red lines that our intel community believes exist. I’m certainly not going to share them publicly, but this is not an ill-conceived idea. When that moment comes is when their program matures and goes across these red lines.”

North Korea claims to have successfully tested a new type of intercontinental ballistic missile capable of striking the U.S. mainland, but it has yet to show it has a nuclear warhead capable of surviving reentry into the Earth’s atmosphere. Still, Graham worried North Korea might share technology to abet nuclear terrorism.

Graham, too, dismissed the idea of an American surgical strike, but said the U.S. must maintain the threat of military force to deny North Korea’s ability to hit America, and to convince China — which doesn’t want a U.S.-North Korea war — to maintain pressure on Pyongyang.

“If China really believes Trump would use military force coming from North Korea, I believe they would change their behavior,” Graham said. “They own the North Korean economy.”

There should be no illusions of an easy U.S. military operation against North Korea, Graham said.

“I don’t think you can surgically strike North Korea,” Graham said. “When I say the military option is the last resort, I mean it, because thousands of people can be killed.”

After a meeting of U.S. allies Tuesday on how to beef up the sanctions pressure, Secretary of State Rex Tillerson stressed that the Trump administration seeks a diplomatic resolution in the nuclear standoff, but he said the North has yet to show itself to be a “credible negotiating partner.” He said U.S.-North Korea talks would require a “sustained cessation” of threatening behavior.

“We all need to be very sober and clear-eyed about the current situation,” Tillerson said when he was asked whether Americans should be concerned about the possibility of a war. He said North Korea has continued to make significant advances in its nuclear weapons through the thermonuclear test and progress in its intercontinental missile systems.

“We have to recognize that the threat is growing and that if North Korea does not choose the pathway of engagement, discussion, negotiation then they themselves will trigger an option,” he said.