President Trump drew "an absurd red line" with his latest promise to punish North Korean belligerence, according to a senior House Democrat.

"Kim Jong Un will call his bluff as America's adversaries watch," New York Rep. Eliot Engel, the top Democrat on the Foreign Affairs Committee, said Tuesday evening.

Trump warned North Korea to expect "fire and fury" if it continues to destabilize the region, after the regime threatened "physical" retaliation for U.S.-led international sanctions. North Korea also reminded South Korea that it can turn the capital city of Seoul into "a sea of flame." The pariah state has been developing missiles capable of delivering nuclear weapons to the United States, alarming American leaders in both parties.

"President Trump has again undermined American credibility by drawing an absurd red line, committing to respond to North Korea's bluster and missile tests with ‘fire and fury like the world has never seen,'" Engel said. "Make no mistake: North Korea is a real threat, but the president's unhinged reaction suggests he might consider using American nuclear weapons in response to a nasty comment from a North Korean despot."

Trump's team touted the remarks as a "strong" warning to the North Koreans. "I think the president's comments were very strong and obvious," White House counselor Kellyanne Conway said during a Tuesday briefing.

Engel's criticism suggests a Democratic willingness to argue that Trump is weakening U.S. credibility, a potentially potent line of attack on the domestic political front. Republicans hammered then-President Barack Obama for declining to authorize airstrikes after Syrian President Bashar Assad used chemical weapons in defiance of his red line, a decision that even some former members of the Obama administration believe had ripple effects around the world.

"America's security is based not just on the strength of our armed forces but on the credibility of our commander-in-chief," Engel said. "Today President Trump's reckless behavior and impulsive outburst undermined the security of the American people, and that of our friends and allies."