Switzerland said on Friday it was tightening security on Friday ahead of next week"s summit between U.S. President Joe Biden and Russian President Vladimir Putin, deploying thousands of police and troops in Geneva to guard against any terrorist threat. Biden and Putin are to meet at the Villa La Grange along Lake Geneva on June 16, their first face-to-face since Biden took office, for what promises to be heated talks on issues from nuclear arms control to cyber attacks. read more "We are on the eve of a historic moment," Stephane Theimer, deputy director of Swiss federal police, told reporters at the park surrounding the 18th-century villa, as a Swiss army helicopter did a flyover. "The terrorist threat in Switzerland and in Europe remains high. Other threats from violent extremist groups are also relevant," he said. "We are on high alert with a significant deployment of forces." The federal government in Bern on Friday declared a temporary restriction on Geneva air space from June 15 to 17. Local authorities, who have put barricades and barbed wire around the park, said they would shut down the lakefront city centre. "The lakefront will be completely locked down on the 16th, for about 24 hours - no pedestrians, no vehicles, no boats," said Francois Waridel, head of Geneva police operations. Some 3,000 to 3,500 police will guard the villa, Cointrin airport, diplomatic missions and hotels, he told Reuters. The stately grey villa, which houses a collection of ancient leather-bound books, and its 30-hectare (nearly 75-acre) park, offer a stunning view of Lake Geneva. Federica Orth, a restorer dressed in a paint-splashed white smock, stood on a ladder at the entry to apply paint to gold cornices near the ceiling. "We didn"t have time to do restoration, we are doing touch-ups," she said. A large ground-floor room, featuring a crystal chandelier, rectangular wooden table with yellow silk chairs and a black marble fireplace, could be the main meeting room, but officials said all rooms would be used. "The villa is symmetric, which is practical for meetings. We can give each delegation the exact same number of rooms," Marion Bordier Bueschi, acting head of Geneva protocol, told reporters.