TOKYO -- North Korea on Sunday claimed a "perfect success" for its most powerful nuclear test so far, a further step in the development of weapons capable of striking anywhere in the United States. President Trump, asked if he would attack the North, said, "We'll see."

The latest provocation from the isolated communist country reinforces the danger facing America, Mr. Trump had said earlier in a series of tweets, adding that "talk of appeasement" is pointless.

"They only understand one thing!" Mr. Trump wrote, without elaboration, as he prepared to meet later with his national security team. It was the first nuclear test since Mr. Trump took office in January.

Hours later, after attending church in Washington, the president made his "We'll see" comment in response to a question from reporters.

Mr. Trump tweeted Sunday that he would meet with White House chief of staff John Kelly, Defense Secretary James Mattis and "other leaders" at the White House to discuss tensions with North Korea. In another tweet, he threatened a shutdown of U.S. trade with countries "doing business" with North Korea.

"The United States is considering, in addition to other options, stopping all trade with any country doing business with North Korea," he posted on Twitter.

The precise strength of the explosion, described by state-controlled media in North Korea as a hydrogen bomb, has yet to be determined. South Korea's weather agency said the artificial earthquake caused by the explosion was five times to six times stronger than tremors generated by the North's previous five such tests. The impact reportedly shook buildings in China and in Russia.

In an interview broadcast Sunday on "Face the Nation," CBS News senior national security contributor Michael Morell, a former acting and deputy director of the CIA, said that with every test, North Korean leader Kim Jong Un "demonstrates to us greater and greater capability."

However, "we don't know for sure exactly where he's at," Morell said.

Morell said that Mr. Trump's first option is diplomacy -- to "try to convince this person to step back from the brink."

"That's failed for the last twenty-five years," Morell said. "And there is absolutely no reason to believe it's going to be successful now."

If it does fail, the remaining options are a military one or "acceptance of this capability, containment, deterrence just the way we contained and deterred the Soviet Union," Morell said.

He described both as "very tough" -- and "bad" -- options.

Mr. Trump warned last month that the U.S. military was "locked and loaded, should North Korea act unwisely," and said the U.S. would unleash "fire and fury" on the North if it continued to threaten America. 

The North's latest test was carried out at 12:29 p.m. local time at the Punggye-ri site where it has conducted past nuclear tests. Officials in Seoul put the magnitude at 5.7; the U.S. Geological Survey said it was a magnitude 6.3. The strongest artificial quake from previous tests was a magnitude 5.3.

"North Korea has conducted a major Nuclear Test. Their words and actions continue to be very hostile and dangerous to the United States," Mr. Trump said in his first of a series of tweets Sunday about North Korea.

He branded North Korea "a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success."