TOKYO North Korea conducted its sixth and most powerful nuclear test to date on Sept. 3, ratcheting already-heightened tensions on the Korean Peninsula even higher. Washington has issued yet another warning to Pyongyang, promising a "massive military response" if it or any of its allies is threatened.
The North, for its part, is unlikely to back away from its vow to conduct more such tests, as they help leader Kim Jong Un maintain his grip on power. U.S. President Donald Trump has insisted he is willing to order military action if Pyongyang crosses his "red line," but he has not yet said what that is. The possibility of a deadly clash over the North's nuclear and other threats is likely to linger at least until he does.
South Korea's Yonhap News Agency reported that Pyongyang appears to be readying another missile launch. South Korea's defense ministry reportedly said the suspected launch would involve an intercontinental ballistic missile.
PRESSURE COOKER "Any threat to the United States or its territories, including Guam, or [to] our allies will be met with a massive military response -- a response both effective and overwhelming," Defense Secretary James Mattis told reporters outside the White House in Washington on Sept. 3. Mattis also said he had met with Trump and was asked to explain the range of military options available to the president.
South Korea is coming around to the stance of the U.S. and Japan, which want to put greater pressure on Pyongyang. Previously, Seoul had stressed peaceful dialogue with its neighbor. Yonhap reported that the South Korean military conducted a drill on Sept. 4, launching missiles into the Sea of Japan.
In the exercise, a target simulating the North's Punggye-ri nuclear test site was hit, demonstrating South Korea's ability to accurately strike such a target in the event of war, Yonhap quoted the Joint Chiefs of Staff as saying.
The three-way cooperation will include economic as well as military pressure on Pyongyang. Seoul, Tokyo and Washington are working on a new package of harsh economic sanctions intended to deal a devastating blow to North Korea's already weak economy, including a total oil embargo.
Trump went a step further: "The United States is considering, in addition to other options, stopping all trade with any country doing business with North Korea," he tweeted on Sept. 3.
For the sanctions to work, however, China must cooperate. The country is believed to export more than 500,000 tons of oil to the North annually.
Russia, too, is maintaining economic ties with the isolated regime.
Even the North's two main friends slammed its latest nuclear test. But both prefer to seek dialogue rather than trying to twist Pyongyang's arm. It is unclear how much support Beijing and Moscow will give to calls for tougher sanctions.
SPOILING THE SHOW For Chinese President Xi Jinping, the nuclear test came at the worst possible time. The leaders of the BRICS nations - Brazil, Russia, India, China and South Africa -- kicked off a series of meetings in the southeastern Chinese city of Xiamen on the same day. North Korea's latest provocation threw cold water on any plans Xi may have had to use the summit to showcase his diplomatic credentials ahead of a pivotal Communist Party congress next month.
Kim Jong Un's determination to gain international recognition as a nuclear power apparently led him to brush aside a U.S. offer of dialogue, which Washington had hoped might nudge Pyongyang toward abandoning its nuclear weapons.
Some experts believe this recognition is growing more likely. North Korea "has raised the capabilities of its nuclear weapons to the maximum degree, to a level at which it would be recognized as a nuclear power," said Moon Sung-mook of the South's Korea Research Institute for National Strategy, noting that the strength of the seismic tremors caused by the blast suggests the country probably succeeded in detonating a hydrogen bomb.
If it has indeed successfully tested such a warhead, and if it is capable of mounting one on an ICBM, the threat to the U.S. increases dramatically. Some North Korea watchers say the country continues to spend a large chunk of its resources on nuclear weapons development, even as economic sanctions bite. They see Pyongyang's strategy as entering into arms control talks with Washington only after it has demonstrated its nuclear prowess.
While Japan, the U.S. and South Korea are moving in lockstep to seek stronger sanctions against North Korea, Tokyo and Seoul are in a nervous guessing game regarding where, precisely, Trump's red line lies. Takashi Kawakami, president of Takushoku University's Institute of World Studies, said North Korea has already crossed that line by carrying out a nuclear test after firing an ICBM that can reach the U.S.
"The U.S. will work steadily to prepare for military action," Kawakami said. But, he added, "If China expresses its intention to defend North Korea, the U.S. will not launch an attack against the country." Another key question is whether the American public would support such a move, he said.
If the U.S. does launch a military strike, North Korea is likely to counterattack with ferocity, posing a serious security threat to both Japan and South Korea.
There are more than 200,000 Americans living in South Korea, including servicemen, and some 60,000 Japanese nationals, including tourists. Any military action against the North could cause massive U.S. and Japanese casualties, in addition to a devastating South Korean toll.