Police in Japan are stepping up security for an upcoming visit by US President Donald Trump.

They plan to mobilize about 25,000 officers, the most for a US presidential visit.

Trump is visiting as a state guest from Saturday through Tuesday. He is to meet Emperor Naruhito and Empress Masako, and hold a summit with Prime Minister Shinzo Abe.

Police have strengthened security measures for so-called soft targets, where many people gather.

A total of 25,000 officers from Tokyo and neighboring prefectures are to carry out a 24-hour watch.

Police plan to impose tight security at key facilities in the capital, including the Imperial Palace and embassies.

They are to deploy armed counterterror units and others equipped with jamming devices to counter suspicious drones.

Particular security measures will be required at the Kokugikan sumo arena in Tokyo. Trump and the first lady plan to visit the arena with Abe and his wife on the final day of the Summer Grand Sumo Tournament.

They're expected to watch bouts from seats near the ring at the center of the arena, requiring alert for possible threats from every direction, including above.

Officers are to be deployed near the seats, as fans sometimes throw seat cushions after exciting matches. Police also plan to carry out ID checks of attendees in some seats and use metal detectors.