The U.S. government has proposed the latter half of May as the timing for President Joe Biden's visit to Japan to attend a "Quad" summit that will also involve the leaders of Australia and India, a diplomatic source said.

Arrangements have been under way for Biden's first visit to Japan since becoming president in 2021. Last month, he signaled to Prime Minister Fumio Kishida during a virtual meeting that he intends to travel to Japan in late spring for the Quad meeting.

The Biden administration views the partnership of the four major democracies in the Indo-Pacific as key amid efforts to push back against China's growing military assertiveness and economic influence in the region.

During his envisioned visit to Japan, Biden will also likely hold the first in-person bilateral meeting with Kishida, who took power last October, apparently to demonstrate the importance of the relationship with the key U.S. ally in Asia at a time when North Korea is frequently test-firing ballistic missiles.

The source said Biden's trip to Asia might also include a stop in South Korea, another close U.S. ally.

Elections in South Korea and Australia, as well as Biden's tight schedule, however, may complicate the planning.

The South Korean presidential election to pick the successor to Moon Jae-in is scheduled for March, with the new president being sworn in on May 10. An Australian parliamentary election will be held by May.

Biden has a busy diplomatic schedule in the first half of June and is also expected to attend the Group of Seven summit later in the month in Germany.