Nancy Pelosi, US House Speaker, arrived in Japan on Thursday for the final stop on her Asian tour, after a visit to Taiwan that incensed China.
The politician was disembark from her plane at the Yokota Air Base in Tokyo, before greeting the US ambassador and other officials with hugs and handshakes.
After Pelosi became the highest elected US official to step foot on the self-ruled island in 25 years, Beijing has launched large-scale military drills in the waters around Taiwan.
The 82-year-old politician defied a series of stern threats from China to meet Taiwanese leaders on Wednesday, saying her trip made it unequivocally clear that the United States would not abandon a democratic ally.
It is Pelosi's first trip to Japan since 2015 when she arrived from South Korea, where her schedule included a visit to the border with nuclear-armed North Korea.
On Friday, the prime minister Fumio Kishida will meet for breakfast, Japan's foreign ministry said, to discuss the two countries' alliance and issues of shared interest.
Pelosi is also scheduled to speak about international affairs with Japan's House of Representatives Speaker Hiroyuki Hosoda.
Japan, a key US ally, has lodged a diplomatic protest with China over its massive military exercises encircling Taiwan, which began on Thursday.
Just before Pelosi arrived, defence Minister Nobuo Kishi said five ballistic missiles fired by China were believed to have landed in Japan's exclusive economic zone.
Some parts of Japan's southernmost island region, Okinawa, are close to Taiwan, as are islets at the centre of a long-running dispute between Tokyo and Beijing.
In May, US President Joe Biden angered Beijing when he said US forces would defend Taiwan militarily if China tried to take control of the island by force - prompting Beijing to warn that the US was playing with fire Biden and his team insisted that their decades-old approach to Taiwan remained in place.
This includes arming the democratic island for its own defence, acknowledging China's legal sovereignty, and expressing strategic ambiguity on whether American troops would intervene if China invaded the territory.