Around 18,000 police officers will be mobilized in Tokyo to tighten security during visits by the leaders of the United States, India and Australia for meetings with Prime Minister Fumio Kishida next week, police said Thursday.

Traffic restrictions will be imposed on the Metropolitan Expressway for three days from Sunday, when U.S. President Joe Biden is scheduled to arrive for a summit with Kishida on Monday and a "Quad" meeting — also to be attended by Indian Prime Minister Narendra Modi and the leader of the party that wins Australia's general election this weekend — the following day.

As the Metropolitan Police Department expects that the tense international environment amid Russia's invasion of Ukraine could increase the risk of attacks and disruptions, they will also deploy riot police and a security team to respond to drones, an official at the department said.

On Thursday, a riot police unit inspected a road near the U.S. Embassy in Tokyo.

Tokyo police will also strengthen measures against attacks on "soft targets," which are typically less protected than government or military facilities but could attract a large crowd, such as the leaders' accommodations, Tokyo Station and Haneda Airport in the capital.

The leaders are expected to discuss Russia's invasion of Ukraine during the Quad summit on Tuesday, among other issues.