US President Donald Trump warned Thursday that it would be a "very sad day" for North Korea if he responded to its provocations with military action.

Trump made the remark as tensions have soared over North Korea's sixth and most powerful nuclear test over the weekend.

"Military action would certainly be an option," he said during a press conference with the emir of Kuwait at the White House. "Is it inevitable? Nothing is inevitable."

He added it would be "great" if there could be another solution, but "talking, talking, talking" has not worked over the past 25 years.

"I would prefer not going the route of the military, but it's something certainly that could happen" Trump said.

Boasting that the US military has never been stronger, with the best equipment in the world, he added: "Hopefully we're not going to have to use it on North Korea. If we do use it on North Korea, it will be a very sad day for North Korea."

Responding to a reporter's question about whether he could tolerate a nuclearized North Korea if it is contained and deterred, he dodged a direct answer.

"I'm not negotiating with you," he said. "Maybe we'll have a chance to negotiate with somebody else, but I don't put my negotiations on the table."

Trump accused past administrations of talking about their strategies, before adding, "But I can tell you that North Korea is behaving badly, and it's got to stop." (Yonhap)