The Trump administration warned Sunday of a "massive military response" against North Korea and President Trump threatened to halt trade with China after Pyongyang conducted an alarmingly powerful nuclear test.
The rhetoric heated up after North Korea claimed it tested a miniaturized hydrogen bomb that could be transported on a ballistic missile. Trump declined to dismiss the possibility of a U.S. attack on North Korea, responding to a reporter's question by saying only, "We'll see."
The president met with his national security team on the expanding crisis. Afterward, Defense Secretary Jim Mattis warned that any threat to the U.S. or its allies would be met with a "massive military response."
"We have many military options, and the president wanted to be briefed on each one of them," Mattis said outside the White House. "We are not looking to the total annihilation" of North Korea.
Reports of the nuclear test, North Korea's sixth and the first since last September, drew swift condemnation from the international community. The leaders of South Korea, Japan and the European Union immediately called for additional U.N. sanctions against the isolated, impoverished nation of 25 million people.
U.S. Treasury Secretary Steven Mnuchin told Fox News Sunday he was working on a new sanctions package.
Neighboring South Korea estimated the blast had a strength of 100 kilotons — several times more powerful than previous tests or the bombs dropped by the U.S. on two Japanese cities in World War II.
There was no immediate confirmation outside North Korea that the test involved a hydrogen bomb, or that it was small enough to be loaded onto a missile. North Korea has made similar, unsubstantiated claims after some of its previous tests.
The latest test appeared to mark a significant step forward in North Korean leader Kim Jong Un's quest for a nuclear missile capable of striking anywhere in the United States.
"North Korea has conducted a major Nuclear Test. Their words and actions continue to be very hostile and dangerous to the United States. ..." Trump said in the first of several tweets about Sunday's test.
Trump tweeted that North Korea is a "great threat and embarrassment to China, which is trying to help but with little success."
Then, later: "The United States is considering, in addition to other options, stopping all trade with any country 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.— Donald J. Trump (@realDonaldTrump) September 3, 2017
Trump has consistently pressed China, North Korea's primary trading partner by far, to use its considerable economic influence over Pyongyang to halt the North's nuclear buildup. China has its own concerns on the Korean Peninsula and has no interest in any solution that could lead to a unified, democratic Korea.
China's Foreign Ministry said it would work with the international community to implement U.N. sanctions.
"Today, the Democratic People's Republic of Korea, despite universal opposition from the international community, conducted another nuclear test," China's Foreign Ministry said in a statement. "The Chinese government expresses firm opposition to and strong condemnation of the test."
Russian President Vladimir Putin was in China for an economic summit and discussed the test with Chinese President Xi Jinping, the Kremlin said. Putin also spoke by phone with Japanese Prime Minister Shinzo Abe, who called for an emergency session of the United Nations Security Council to discuss stricter sanctions against the Kim regime.
Putin's Foreign Ministry issued a statement calling for a "reasonable and balanced " approach to the crisis. The statement questioned the growing international call for more sanctions, noting that sanctions so far had "not led to any positive outcome.”
..North Korea is a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success.— Donald J. Trump (@realDonaldTrump) September 3, 2017
Trump's Twitter wrath also was directed at the government in Seoul: "South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!"
South Korean President Moon Jae-in was elected in May by promoting a policy of negotiation with North Korea, even suggesting he would visit Pyongyang. On Sunday, however, his government denounced North Korea's latest test and vowed to push for more U.N. sanctions aimed at further isolating Seoul's communist neighbor.
Moon "will never allow North Korea to continue advancing its nuclear and missile technologies," said Moon's national security adviser, Chung Eui-yong.
South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!— Donald J. Trump (@realDonaldTrump) September 3, 2017
Complicating U.S. relations with South Korea is a report by The Washington Post that Trump had instructed advisers to prepare to withdraw from a free-trade agreement with South Korea. The Post said Mattis and national security adviser H.R. McMaster were among the high-ranking officials opposing the plan.
On North Korean television, a news reader called the test a “complete success” and said the “two-stage thermonuclear weapon” had “unprecedented” strength. U.S. Geological Survey data showed that a magnitude-6.3 seismic event was detected Sunday in North Hamgyeong Province.
Analysts said Sunday's test indicates that North Korea is getting close to posing a credible nuclear threat to the U.S.
"This looks like a major improvement in yield," said Chad O’Carroll, CEO and founder of Seoul-based Korea Risk Group, a risk advisory firm specializing in North Korea.
North Korea flew a Hwasong-12 over northern Japan last week, the first such overflight by a missile capable of carrying nukes, in a launch that Kim described as a “meaningful prelude” to containing Guam, the home of major U.S. military facilities, and more ballistic missile tests targeting the Pacific.
O’Carroll said he expects North Korea to soon launch a new test of an intercontinental ballistic missile (ICBM) with a long-range trajectory of thousands of miles into the Pacific Ocean.
“If one or two more ICBMs can be tested successfully in this way, North Korea would then announce the battle-ready deployment of its ICBM force,” he said.