US House of Representatives Speaker Nancy Pelosi is meeting Japanese officials in Tokyo, following a visit to Taiwan that Beijing answered with unprecedented military drills and missile launches.
Pelosi will meet officials on Friday after arriving in Japan following a visit to South Korea on Thursday, where she vowed support to denuclearise North Korea.
In Tokyo, she and Prime Minister Fumio Kishida met for discussions on Friday morning. She is also expected to meet her Japanese counterpart Hiroyuki Hosoda, speaker of the more powerful lower house of parliament.
Kishida condemned China's firing of ballistic missiles during military drills around Taiwan, five of which Tokyo believes landed in its exclusive economic zone.
The missile launches are a "serious problem that impacts our national security and the safety of our citizens," Fumio Kishida told reporters after meeting Pelosi for breakfast.
Pelosi's brief trip to Taiwan, where she arrived unannounced with a congressional delegation late on Tuesday and left on Wednesday, marked the highest-level US visit to the island state, which China says is its inseparable province, in 25 years.
It also came as Tokyo, one of Washington's closest allies, has been increasingly alarmed about China's growing might in the Asia-Pacific and the possibility that Beijing could take military action against Taiwan.
"China has chosen to overreact and use the speaker's visit as a pretext to increase provocative military activity in and around the Taiwan Strait," White House spokesperson John Kirby told reporters.
"The temperature's pretty high," but tensions "can come down very easily by just having the Chinese stop these very aggressive military drills," he added.
Largest Chinese drills in area
Pelosi lauded Taiwan's democracy and pledged American solidarity. Beijing responded with military drills that a state broadcaster said would be the largest by China in the Taiwan Strait, including live firing on the waters and in the airspace around the island.
Five missiles landed in Japan's exclusive economic zone, prompting Tokyo to lodge a strong protest through economic channels.
Japan, whose southernmost islands are closer to Taiwan than Tokyo, has warned that Chinese intimidation of Taiwan is an escalating national security threat.
PM Kishida's Liberal Democratic Party (LDP) has also pledged to double military spending to 2 percent of GDP.
Tensions between Japan and China ramped up a notch on Thursday when China announced that a meeting between the two nations' foreign ministers, set to take place on the sidelines of an ASEAN meeting in Cambodia, had been called off due to its displeasure with a G7 statement urging Beijing to resolve Taiwan tension peacefully.