President Trump said Thursday his warning that the U.S. would meet North Korea with "fire and fury" may not have been tough enough.

"They've been doing this to our country for a long time, for many years, and it's about time someone stuck for the people of this country and for the people of other countries," he said in Bedminster, N.J., in response to criticisms of his comments this week, according to a pool report. "If anything, maybe that statement wasn't tough enough."

The president also urged the rogue regime to "get their act together," and said the U.S. military, as well as other world leaders, back the U.S. "100 percent."

When asked if he had any assurances to Americans worried about Pyongyang's escalation of threats, Trump said the U.S. would retaliate strongly to any action that country takes.

"If North Korea does anything in terms of even thinking about an attack of anybody that we love or we represent or our allies or us, they can be very, very nervous. I'll tell you why," Trump said. "And they should be very nervous because things will happen to them like they never thought possible, OK? [Kim Jong Un] has been pushing the world around for a long time."

Trump issued a stern warning to North Korea on Tuesday, days after the U.N. Security Council voted to sanction Pyongyang.

"North Korea best not make any more threats to the United States," Trump said. "They will be met with fire and fury like the world has never seen."

Trump's comments appeared to be prompted by a statement issued to the state-run Korean Central News Agency, which said "packs of wolves are coming in attack to strangle a nation."

Congressional Democrats criticized Trump for his comments, but Secretary of State Rex Tillerson and Secretary of Defense James Mattis came to the president's defense.

Trump reiterated Thursday there were no "mixed messages" coming out of his administration.

When asked about Trump's comments Wednesday, Heather Nauert, spokeswoman for the State Department, said the U.S. was speaking with "one voice" on North Korea. On Thursday, Nauert reiterated that U.S. policy toward North Korea hasn't changed after Trump's reiteration.