WASHINGTON — High-level analysts here are warning of the rising danger of nuclear war with North Korea while advocating for legislation pursued by Democrats in Congress that would declare the Korean War is over — whether Pyongyang agrees or not.

Within hours after North Korea showed off its deadliest weapons, the Americans were, at an anti-war conference, being blamed for failing to come to terms with the North. The conference attendees cheered the speakers for their impassioned criticism of American policy on North Korea.

All those at the gathering at George Washington University seemed oblivious to the show at Pyongyang. They fixed on legislation that’s widely seen as leading to withdrawal from South Korea of America’s 28,500 troops and undermining the longstanding Washington-Seoul alliance.

“For three decades we’ve had an opportunity to constrain North Korea’s nuclear weapons,” the former director of the Los Alamos National Laboratory, Siegfried Hecker, told the gathering. “We failed.”

Next up, a retired air force lieutenant general, Daniel Leaf, was even more emphatic. “I’m a fighter pilot,” said General Leaf, who served for four years in South Korea. “I have engaged with nuclear weapons. We are one bad step away from a nuclear war with North Korea. It could happen.”

A former army colonel, Ann Wright, who had a second career as a diplomat, accused Washington of having “undercut the opportunities we had.” It was, she said, “a dangerous world out there” and war “could erupt at any time.”

The three talked at the end of three days of marching, chanting slogans, and seeing members of Congress as they pressed the case for passage of the “Peace on the Korean Peninsula Act.” That measure that would formally end the Korean War, at least as far as the Americans are concerned.

Another thing the conferees failed to discuss, though, is that the Constitution fails to grant Congress the power to make peace. Giving Congress that power was discussed at Philadelphia in 1787, but the constitutional convention rejected the proposal. 

The Constitution does not explicitly grant peace-making powers to any part of the American government, leading to suggestions that the only way peace can be made is if an enemy is defeated.

Proponents of the bill, though, including its leading sponsor, Brad Sherman, a representative from California, seized on the 70th anniversary Thursday of the signing of an armistice that stopped the fighting. He sought to mark the moment to publicize their message and galvanize support for their cause.

The bill, which won as sponsors more than 30 other members of Congress, is far from even reaching the floor for a vote, but Mr. Sherman often echoes the argument of its impassioned advocates.

“While the conflict ended in 1953, nearly 70 years later we technically remain in a state of war with North Korea,” he said. “This is why I introduced the Peace On the Korean Peninsula Act.” 

Mr. Sherman cited an organization called “Women Cross DMZ,” named for a group of 31 women who visited North Korea in 2013, then made it to the South across the Demilitarized Zone between the two Koreas, and the American Friends Service Committee as championing the bill. It would, he said, “create an end-of-war declaration and start serious, urgent diplomatic engagement with North Korea to lower tensions and avoid confrontation.” 

No one at the conference mentioned that North Korea, hours  before, had staged a parade through central Pyongyang displaying its latest intercontinental ballistic missiles and drone aircraft. 

The North has been spurning pleas from both Washington and Seoul for a return on negotiations ever since President Trump walked out of his second meeting with North Korea’s leader Kim Jong-un in the Metropole Hotel at Hanoi in February 2019.

Nor did anyone mention the presence in Pyongyang of top officials from North Korea’s two Korean War allies, Russia’s defense minister, Sergei Shoigu, and a member of the politburo of the ruling Chinese Communist Party, Li Hongzhong, both of whom were present to observe the parade.

Mr. Hecker, however, did observe that North Korea, after having sought some form of relations with Washington, perhaps an exchange of liaison offices, was “going back to aligning itself with China and Russia.”

A University of Chicago historian, Bruce Cumings, keynoting the conference, was still more emphatic about a series of failures and blunders that accounted for the escalating tensions on the Korean peninsula and the region.

Mr. Cumings, author of a number of books on recent Korean history, particularly blamed American attempts at “intimidation” of North Korea by sending heavy bombers on flights just below the DMZ. This pattern, he suggested, accounted for North Korea’s investment in a nuclear program.

By now, Mr. Hecker said, it may be too late to get the North to reverse course.

“It’s going to be a very difficult journey to get to denuclearization,” he said. Rather than make denuclearization a precondition, he believed the war had to come to a formal end.

“We can agree on the need for a peace treaty,” he said. “It’s really important to expand the dialogue. Why don’t folks get the immediacy of the threat?”

General Leaf warned of the danger of misunderstandings “in the fog of war.” Our side “needs to be wholly rational,” he said. The answer: “unequivocal pursuit of a peace treaty.”

Mr. Hecker advised asking the North Koreans, “How important is a peace treaty, and how would you go about it?” 

Left unmentioned was that North Korea isn’t responding to messages and has a long record of violating every agreement it’s ever made going back the first North-South negotiations more than 50 years ago before beginning its pursuit of nuclear weapons.