Tokyo police are on heightened alert ahead of the start of US President Joe Biden's visit to Japan. His visit to Japan comes as international tensions are running high over Russia's invasion of Ukraine.

Biden is scheduled to arrive at Yokota Air Base in the Japanese capital late Sunday afternoon.

During his three-day visit, he will meet Emperor Naruhito and hold talks with Prime Minister Kishida Fumio. The president is also set to attend a summit of the Quad nations of Japan, the United States, Australia and India.

The Metropolitan Police Department is mobilizing 18,000 officers to guard the State Guest House -- the venue for the summit between Biden and Kishida -- and other places where many people gather. The figure is the highest for a US president's visit to Japan.

Police plan to take thorough measures during Biden's stay to prevent terrorist attacks. They will include using dogs trained to detect explosives for patrols and keeping an emergency response team on standby.

Police say traffic on the Metropolitan Expressway and other roads in surrounding areas will be restricted when Biden travels by car. They also plan to inspect vehicles at checkpoints.