In an open letter to international leaders, a North Korean parliamentary committee has called for “sharp vigilance” with regards to the United States, saying recent remarks by US President Donald Trump at the United Nations General Assembly (UNGA) constituted a declaration of war against Pyongyang.

The Foreign Affairs Committee of the Supreme People’s Assembly, North Korea’s Parliament, released the letter on Sunday, condemning Trump’s “ignorant” threats made during his UN speech, the official KCNA reported on Monday.

In his first speech at the UNGA, Trump threatened to “totally destroy” North Korea if necessary.

The letter described Trump’s comments as an “intolerable insult to the Korean people, a declaration of war against North Korea and grave threats to the global peace.”

“If Trump thinks that he would bring North Korea, a nuclear power, to its knees through nuclear war threat, it is a big miscalculation and ignorance,” read the letter.

The letter said that, “From the first day of his office, Trump has conducted high-handed and arbitrary practices, scrapping international laws and agreements,” giving priority to the US’s own interests “at the expense of the whole world.”

Trump, who had formerly threatened Pyongyang with “fire and the fury like the world has never seen,” renewed the threat at the UNGA, saying, “The United States has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea.”

He called North Korean leader Kim Jong-un a “rocket man” who is “on a suicide mission.”

In making that specific remark, Trump reportedly ignored some of his top aides, who had warned him that making personal attacks on the North Korean leader would backfire and destroy any chances of starting talks with Pyongyang over its nuclear and missile programs, according to The Los Angeles Times.

Kim responded to Trump’s UN remarks by saying that he “will consider with seriousness exercising of a corresponding, highest level of hard-line countermeasure in history.”

North Korean Foreign Minister Ri Yong-ho also said that Pyongyang was considering a powerful nuclear weapon test in the Pacific Ocean in response to Trump’s threats.

Speaking before the United Nations, Ri later said Pyongyang was ready for a preemptive nuclear attack if needed.

Then on Saturday, Trump tweeted, “Just heard Foreign Minister of North Korea speak at UN. If he echoes thoughts of Little Rocket Man, they won’t be around much longer!”

There were also military maneuvers held by US bombers over waters east of North Korea. The Pentagon said Saturday that its bombers from Guam and Okinawa, in Japan, had flown in international airspace over the waters in “a clear message that the President has many military options to defeat any threat.”