President Trump said Friday that North Korean leader Kim Jong Un will “regret it fast” if he threatens or attacks any U.S. territory or ally, while acknowledging his team is considering military options “very carefully.”

“If he does anything with respect to Guam or any place else that’s an American territory or an American ally, he will truly regret it and he will regret it fast,” Trump told reporters Friday afternoon at his New Jersey golf club. 

The warning was the latest escalation in what has become a war of words between the two countries. Trump has spent the week turning up the heat on North Korea, specifically warning the regime of real consequences if it carries out an attack on Guam, the U.S. territory the country has threatened.

“This man will not get away with what he’s doing, believe me,” Trump said of Kim.