The United States has flown heavy bombers over the Korean peninsula in a joint drill with Japanese and South Korean warplanes, potentially raising tensions ahead of US President Donald Trump's first visit to Asia starting tomorrow.
North Korea, which sees such drills as dress rehearsals for a strike on its leader Kim Jong Un, has hit out against what it called a "surprise nuclear strike drill". But the US Pacific Air Forces insists the drill was planned in advance and is "not in response to any current event".
Seoul, meanwhile, warned yesterday that the North could be gearing up for its first missile test since Sept 15, as intelligence officials note brisk activity near its test sites.
North Korea will dominate Mr Trump's agenda as he visits Japan, South Korea, China, Vietnam and the Philippines. National Security Adviser H.R. McMaster said Mr Trump will continue to impress on leaders that the world is "running out of time" to cope with the crisis. Pyongyang has lobbed two missiles over Hokkaido and held a sixth nuclear test this year, while engaging in a war of words with the US.
Japanese Prime Minister Shinzo Abe and Mr Trump have insisted that China do more to rein in North Korea. The US on Thursday denied China's Bank of Dandong access to its financial system, alleging that the bank is used by the North to launder funds and evade sanctions.
China's Global Times said on Thursday all sides may have to make concessions to reach a peaceful solution to the nuclear issue. "China is playing the most difficult role in the process, and is the real hope of peacefully addressing the crisis. Neither side should press China in an extreme way," it said in an editorial.
But Mr Trump warned in an interview with Fox News that day that Japan, as a "warrior nation", could take matters into its own hands if China does not do enough to curtail the crisis.
Japan, while bound by a war-renouncing Constitution that Mr Abe wants to amend, is mulling over the acquisition of "first strike" capabilities in the name of defence should an attack be deemed imminent.
Chinese President Xi Jinping sent a note earlier this week to Mr Kim urging for stable Sino-North Korea ties, the North's state-run Korean Central News Agency said. The North called Mr Trump's attempts to woo Mr Xi - including a comment that Mr Xi was "pretty terrific" on Pyongyang - "brown-nosing words (that) are utterly sickening and disgusting".