Indonesian Navy's Frogmen's Force (Paska TNI-AL) and the U.S. Navy Seal have carried out a joint military exercise as an effort to boost skills to prevent terrorism particularly at sea, an officer said on Tuesday. Spokesman of the Indonesian Navy for western fleet command Supriyono said that the 24-day exercise started on Monday in waters off Lampung province in western parts of Indonesia and was participated by one platoon (40 to 50 personal) from both countries. 'The purpose of this joint exercise is to sharpen and increase their professional skills, which then would be useful in tackling the danger of terrorism,' he told Xinhua over phone. Indonesia has been hit by a series of major terrorist acts since 2000 and the United States citizens and its facilities in domestic and overseas have been targeted by terrorism. Indonesia has been attacked by terrorist acts such as the churches explosion in 2000, Bali bombings in 2002 and 2005, JW Marriot Hotel blasts in 2003, Australian embassy bombings in 2004 and the recent suicide bombings at JW Marriot Hotel and Ritz Carton Hotel, killing more than 260 people. 