Dutch police will increase security at two major outdoor events in Amsterdam and Rotterdam.
Police said 400 officers will be on patrol at the annual tall ships event, called Sail Amsterdam 2005, Aug. 17-22, which is expected to draw 2.5 million visitors.
Police and hundreds of private security guards have been granted extra powers to conduct random searches of people and their belongings. Dozens of security cameras will record the crowd's movements.
Similar measures were announced for the Fast Forward Dance Parade in Rotterdam on Saturday, where hundreds of thousands of revelers dance to techno music in the streets as disc jockeys drive through the city on trucks.
Authorities said they had no specific indications of an imminent attack, but the Netherlands remains a potential terror target.
The country was shaken by the murder Nov. 2 of Dutch filmmaker Theo van Gogh by an Islamic extremist with proved Chechen links, Mohammed Bouyeri, who allegedly is part of a network that plotted the murder of politicians. Several underground groups are believed to be active in the country, the AP reports.
The United States and NATO are conducting provocative activities both in airspace and waters of the Black Sea, Russian Defense Minister Sergei Shoygu said