The story behind Trump's 'fire and fury' comments on North Korea The president used the phrase behind closed doors in recent days.

 -- President Donald Trump went rogue with his comments on North Korea Tuesday, using bellicose language not vetted or approved by his national security team, ABC News has learned.

While the exact language surprised some presidential aides, White House officials say it was a strategic decision by the president to ramp up the rhetoric. The timing, tone and intent of the statement were discussed in advance, according to sources.

During a briefing on the opioid crisis Tuesday at his Bedminster, New Jersey, golf club, the president was expecting a question on North Korea from reporters and had an answer ready to go, the sources said. Several aides said that they were aware Trump would take a hard line in his comments to the press.

Several Trump aides told ABC News that the president has used the phrase "fire and fury" behind closed doors in recent days in reference to the North Korean situation. He did not, however, discuss plans to make a public proclamation of the rhetoric.

“[White House Chief of Staff John] Kelly and others on the [National Security Council] team were well aware of the tone of the statement of the president prior to delivery. The words were his own,” White House press secretary Sarah Sanders said in a statement Wednesday.

“The tone and strength of the message were discussed beforehand. [Kelly and the National Security Council team] were clear the president was going to respond to North Korea’s threats following the sanctions with a strong message in no uncertain terms,” Sanders said.

A senior administration official said that while Trump appeared to look down at a piece of paper when he spoke Tuesday, the president did not have the North Korea comments written out.

Deputy press secretary Lindsay Walters told reporters Wednesday that Kelly and the president "are and have been in constant contact with members of the [National Security Council] team” on North Korea.

Walters said the consultations occurred both before and after the president made his “fire and fury” comments Tuesday but suggested, as other officials have privately, that the verbal threat to the North Korean regime was not broadly coordinated in advance.