President Trump on Monday announced that his administration has redesignated North Korea as a state sponsor of terror, a move aimed at increasing pressure on Pyongyang nearly a decade after the George W. Bush administration removed the rogue nation from the list.

Trump made his decision public during a brief photo op at a Cabinet meeting, calling it “a very critical step” that “should've happened a long time ago.” The president cited assassinations by the dictator Kim Jong Un's regime carried out on foreign soil, as well as the treatment of American college student Otto Warmbier, who died in June days after he was released in a coma by the North after spending 17 months in captivity.

Trump vowed that Pyongyang will face further sanctions in the near future that will amount to the “highest level of sanctions by the time it’s finished.”

The White House had signaled during Trump's Asia trip this month that the president was likely to make the designation. The North spent 20 years on that list before being removed in 2008 by the Bush administration for meeting nuclear inspection requirements. Pyongyang later violated the agreement.

In a speech to the South Korean national assembly two weeks ago, Trump cited atrocities carried out by the Kim regime and called the North “a hell that no person deserves.” Among other acts, Kim's regime stands accused of carrying out the assassination of his half brother, Kim Jong Nam, with a chemical nerve agent at a Malaysian airport in February.

"Importantly, this is just continuing to point out North Korea's illicit, unlawful behaviors internationally," Secretary of State Rex Tillerson said at the White House daily briefing Monday. "And we felt it was important to reimpose the designation for that reason."

Tillerson cited other recent sanctions from the United States and the United Nations on the North and added that the redesignation "continues to tighten the pressure on the Kim regime, all with an intention to have him to understand, 'This is just going to get worse until you're ready to come and talk.'"

Iran, Sudan and Syria also are on the list, which is administered by the State Department. According to that agency, sanctions for those nations on the list include “restrictions on U.S. foreign assistance; a ban on defense exports and sales; certain controls over exports of dual use items; and miscellaneous financial and other restrictions.”

Tillerson acknowledged that the North already has been facing so many sanctions that the redesignation of the country on the terror-sponsor list would not add significant new impositions.

"The practical effects may be limited," he said.

Last month, a bipartisan group of House members wrote to Tillerson urging him to add North Korea to the list, citing the deaths of Warmbier and Kim Jong Nam.

“Such acts are not isolated events, but part of a consistent pattern by the Kim regime,” stated the letter, signed by Rep. Edward R. Royce (R-Calif.), chairman of the House Committee on Foreign Affairs, and Rep. Eliot L. Engel (D-N.Y.), the committee's ranking Democrat, among others.

Michael Green, who served as senior Asia director at the National Security Council under Bush from 2001-2005, said the removal of the North from the terror-sponsor list was “very controversial” and turned out to be a “crappy deal” that Pyongyang quickly violated. He added that the Japanese government had lobbied the Bush administration not to remove the North in 2008 until Pyongyang brought resolution to Tokyo's claims that the North had kidnapped at least 17 Japanese citizens in the 1970s.

During his visit to Tokyo two weeks ago, Trump met with families of the dozen Japanese abductees whose cases have not been resolved.

“Putting them back on the list is important symbolically as a demonstration of good faith with Japan,” Green said of North Korea. “It also helps add spin on the ball with sanctions overall.”

Daniel Russel, former NSC senior Asia director under President Barack Obama, agreed that the move was symbolically potent because the lifting of the sanctions represented the “high water mark of U.S.-North Korea efforts to reconcile their differences and negotiate and engage in 2008.”

The re-listing of the North is tantamount to “taking one of the trophies out of the glass case and shattering it,” he said.

Russel said the Obama administration had deliberated over the North's behavior but had been unable to cite a legal rationale for re-listing the country on the terror-sponsor list. He suggested that the Kim Jong Nam assassination provided such rationale for the Trump administration.

Carol Morello contributed to this report.