The Metropolitan Police Department on Thursday set up a task force to oversee security in the capital for U.S. President Barack Obama's scheduled visit on Friday and Saturday.
A total of 16,000 personnel, including some 5,500 members of riot police squads, will be deployed in preparation for possible demonstrations and sabotage by radical groups, as well as for controlling traffic.
"Strengthening security as a matter of course, we will implement full-scale preparations for the president's visit," Chief Cabinet Secretary Hirofumi Hirano told reporters.
Obama arrives Friday afternoon on a whirlwind visit before heading to a Singapore summit.
It will be the highest level of security since Japan hosted a summit of the Group of Eight major economies on northern Hokkaido island in July last year, when around 20,000 police were deployed in Tokyo alone.
Police have set up checkpoints near the U.S. embassy to inspect suspicious vehicles, while anti-riot police were patroling near Tokyo's Yokota Air Base, where an explosive device was reportedly found last month.
Police have sealed off manhole covers and put extra officers on duty at subway stations, which were targeted by a doomsday cult using nerve gas in 1995 in an attack that killed 12 people and injured thousands.
Demonstrators plan to stage a rally Friday and march near the U.S. embassy and the prime minister's office against the U.S. military presence on the southern island of Okinawa, a contentious issue between Tokyo and Washington.
Hirano said the government had received no information indicating a security threat but was taking precautionary measures. "We have taken action, but it has not been based on any information about terrorism," he said.
Obama is to hold talks with Prime Minister Yukio Hatoyama Friday evening and have lunch with the emperor at the Imperial Palace on Saturday before departing for Singapore to attend this year's Asia-Pacific summit.© Wire reports