The designation, announced on Monday, allows the United States to impose more sanctions on Pyongyang, which is pursuing nuclear weapons and missile programmes in defiance of U.N. Security Council sanctions.
"I welcome and support (the designation) as it raises the pressure on North Korea," Japan's Prime Minister Shinzo Abe told reporters on Tuesday, according to Kyodo news agency.
South Korea said it expected the listing to contribute to the peaceful denuclearisation of the North, adding it continued, along with the United States, to seek to bring North Korea to the negotiating table, the country's foreign ministry said in a text message.
Trump's re-listing of North Korea as a sponsor of terrorism comes a week after he returned from a 12-day trip to Asia in which containing North Korea's nuclear ambitions was a centerpiece of his discussions.
"In addition to threatening the world by nuclear devastation, North Korea has repeatedly supported acts of international terrorism, including assassinations on foreign soil," Trump told reporters at the White House.
"This designation will impose further sanctions and penalties on North Korea and related persons and supports our maximum pressure campaign to isolate the murderous regime."
Australian Prime Minister Malcolm Turnbull also backed Trump's decision, saying the move was in line with international efforts to bring the rogue state to its senses.
"Kim Jong Un runs a global criminal operation from North Korea peddling arms, peddling drugs, engaged in cyber-crime and of course threatening the stability of region with his nuclear weapons," Turnbull told reporters in Sydney on Tuesday.
"So we strongly welcome that decision and it mirrors the determination of the international community on bringing North Korea back to its senses."
North Korea was put on the U.S. terrorism sponsor list for the 1987 bombing of a Korean Air flight that killed all 115 people aboard. But the administration of former President George W. Bush, a Republican, removed Pyongyang in 2008 in exchange for progress in denuclearisation talks.
Experts say the designation will be largely symbolic as North Korea is already heavily sanctioned by the United States.
On Monday, South Korean President Moon Jae-in's special security advisor Moon Chung-in told reporters any such designation would be "more symbolic than substance".
The United States has designated only three other countries - Iran, Sudan and Syria - as state sponsors of terrorism.
North Korea is pursuing nuclear weapons and missile programmes in defiance of U.N. Security Council sanctions and plans to develop a nuclear-tipped missile capable of hitting the U.S. mainland. It has fired two missiles over Japan and on Sept. 3 conducted its sixth and largest nuclear test.
South Korea's spy agency said on Monday the North may conduct additional missile tests this year to improve its long-range missile technology and ramp up the threat against the United States.
(Additional reporting by Jeff Mason and David Brunnstrom in WASHINGTON, Chang-Ran Kim in TOKYO and Jane Wardell in SYDNEY; Writing by Michael Perry; Editing by Editing by Lincoln Feast)
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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