The director of the CIA has made an unannounced visit to South Korea as tensions in the region ratcheted up.
The visit comes after North Korea conducted another missile test on Saturday that appeared to fail shortly after launch — the third botched attempt this month. Despite the North's tests seeming unsuccessful, they have provoked hostilities with its Asian neighbours and the US.
Mike Pompeo and his wife were in the South Korean capital on Monday, an embassy official said, although they refused to say how long the visit lasted.
The CIA chief arrived in the country over the weekend for meetings with the head of South Korea's National Intelligence Service and high-level officials in the presidential office, according to South Korean media reports.
North Korea suggested on Monday it would continue its nuclear weapons tests, saying it would build-up its nuclear forces "to the maximum" in a "consecutive and successive way at any moment".
Meanwhile, in a show of its military power, the US sent the nuclear-powered USS Carl Vinson aircraft carrier to waters off the Korean Peninsula to take part in drills with the South's naval forces.
Japan's navy dispatched its largest war ship reportedly tasked with escorting US military ships off the Japanese coast.
The helicopter carrier Izumo departed the Yokosuka port near Tokyo earlier on Monday.
Japanese media reports said it will meet up with and escort a US supply ship, a first-time mission under new security legislation that allows Japan's military a greater role overseas.
They said the US ship is expected to refuel other American warships, including the USS Carl Vinson.
Japan's Defence Ministry said only that the Izumo would participate in an international naval event in Singapore on May 15.
He refused to say whether this meant military action, saying: "I don't know, I mean, we'll see." He added: “We shouldn't be announcing all our moves. It is a chess game. I just don't want people to know what my thinking is.”
Associated Press contributed to this report