UPDATE 1-Trump: U.S. designates N.Korea a state sponsor of terror, triggering sanctions

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WASHINGTON, Nov 20 (Reuters) - President Donald Trump designated North Korea a state sponsor of terrorism on Monday, allowing the United States to impose additional sanctions and penalties against Pyongyang as it continues to pursue nuclear weapons programs.

The Republican president, who has traded personal barbs and insults with North Korean leader Kim Jong Un, said the Treasury Department will announce the additional sanctions against North Korea on Tuesday.

The designation came a week after Trump returned from a 12-day, five nation trip to Asia in which the U.S. president made containing North Korea's nuclear ambitions a centerpiece of his discussions with world leaders.

"Today, the United States is designating North Korea as a state sponsor of terrorism," Trump told reporters at the White House. "Should have happened a long time ago should have happened years ago."

North Korea is pursuing nuclear weapons and missile programmes in defiance of U.N. Security Council sanctions and has made no secret of its plans to develop a missile capable of hitting the U.S. mainland. It has fired two missiles over Japan.

South Korea's spy agency said on Monday North Korea may conduct additional missile tests this year to polish up its long-range missile technology and ramp up the threat against the United States.

Some experts, and U.S. officials speaking privately, have argued that North Korea does not meet the criteria for the designation, which requires evidence that a state has "repeatedly provided support for acts of international terrorism."

Experts also say that the move will be largely symbolic, as North Korea is already heavily sanctioned by the United States. (Reporting by Jeff Mason; Additional reporting by David Brunnstrom; Writing by Doina Chiacu; Editing by Susan Thomas)