North Korea’s parliament convened Tuesday amid heightened tensions on the divided peninsula, with the United States and South Korea conducting their biggest-ever military exercises and the USS Carl Vinson aircraft carrier heading to the area in a show of American strength.

North Korea vowed a tough response to any military moves that might follow the U.S. decision to send the carrier and its battle group to waters off the Korean Peninsula.

“We will hold the U.S. wholly accountable for the catastrophic consequences to be entailed by its outrageous actions,” a spokesman for its Foreign Ministry was quoted as saying by the state-run Korean Central News Agency.

The statement followed an assertion by U.S. Secretary of State Rex Tillerson that U.S. missile strikes against a Syrian air base in retaliation for a chemical weapons attack carry a message for any nation operating outside of international norms. He didn’t specify North Korea, but the context was clear enough.

“If you violate international agreements, if you fail to live up to commitments, if you become a threat to others, at some point a response is likely to be undertaken,” Tillerson told ABC’s “This Week.”

Pyongyang is always extremely sensitive to the annual U.S.-South Korea war games, which it sees as an invasion rehearsal, and justifies its nuclear weapons as defensive in nature. It has significantly turned up the volume of its rhetoric that war could be on the horizon if it sees any signs of aggression from south of the Demilitarized Zone.

“This goes to prove that the U.S. reckless moves for invading the DPRK have reached a serious phase of its scenario,” the North’s statement said, referring to the country by its formal name, the Democratic People’s Republic of Korea. “If the U.S. dares opt for a military action, crying out for ‘pre-emptive attack’ … the DPRK is ready to react to any mode of war desired by the U.S.”

In Washington, White House spokesman Sean Spicer said President Donald Trump has been very clear that it’s “not tolerable” for North Korea to have nuclear-armed missiles.

“The last thing we want to see is a nuclear North Korea that threatens the coast of the United States, or, for that matter, any other country, or any other set of human beings,” Spicer said at the Tuesday news briefing.

Chinese state broadcaster CCTV reported that Trump spoke Wednesday morning Beijing time with Chinese President Xi Jinping about North Korea. It said Xi stressed the need for an end to North Korea’s nuclear weapons program, and that China insists on peace and stability on the peninsula and advocates resolving the problem through peaceful means. Xi said China would maintain “communication and coordination” with Washington over the issue.

Spicer said that Trump spoke last week with Xi about the “shared national interest” in stopping its close ally, North Korea, from having nuclear capabilities, adding that it would be helpful if China was more outspoken on the matter.

“He would welcome President Xi weighing in on this a little bit more,” Spicer said.

Earlier Tuesday, Trump also said that he tried to persuade Xi to put pressure on North Korea in exchange for a good trade deal with the U.S.

“I explained to the President of China that a trade deal with the U.S. will be far better for them if they solve the North Korean problem!” Trump tweeted.

In a second tweet he wrote: “North Korea is looking for trouble. If China decides to help, that would be great. If not, we will solve the problem without them! U.S.A.”

North Korea’s parliament, the Supreme People’s Assembly, nominally the highest organ of government, opened Tuesday with the country’s leader, Kim Jong Un, taking the center seat.

Foreign media are not allowed to attend parliamentary sessions. Initial reports from state media said the meeting went through domestic issues, with Premier Pak Pong Ju making a speech about the latest five-year economic plan, which was announced last year. Another closely watched category on the official agenda is organizational issues, which can mean new appointments to senior positions.

Like other attendees, Kim Jong Un was shown on the North Korean news late Tuesday holding up his assembly membership card to vote on state business.

This year’s meeting kicks off what are expected to be major celebrations, including a large-scale military parade and fireworks, to mark the 105th anniversary of the birth of Kim Il Sung, North Korea’s first leader and “eternal president,” and Kim Jong Un’s late grandfather.

Though the details of the April 15 anniversary — known as the “Day of the Sun” — have not been officially confirmed, Pyongyang residents have been out every day diligently practicing in the city’s squares and parks for the mass event.

The North Korean parliament is often dismissed as rubberstamp because it tends to approve, rather than formulate, policies and laws, but its role is a bit more complex than the facade and spectacle presented to the nation by state-run media.

For one thing, the regularity of its meetings — it usually meets once or twice a year — is, in itself, a sign of stability.

“The SPA gatherings completely undercut any analysis or prognostications that the country is going to collapse. If they failed to convene an SPA session, that would be an indication that there is a fundamental problem among DPRK elites,” said Michael Madden, editor of the North Korea Leadership Watch website.

“If there was an existential problem with the (ruling) Workers’ Party of Korea and the political culture, then they wouldn’t be convening so many people at one time in Pyongyang,” Madden said.

(AP)