SOFIA, Feb. 22 (Xinhua) -- The U.S. army started the deployment of up to 400 troops and heavy weapons to Bulgaria for a joint drill with the Balkan country lasting until Oct. 19, authorities said Friday.

The troops as well as infantry fighting vehicles M2A3 Bradley, helicopters UH-60 Blackhawk and HH-60 Pave Hawk, self-propelled mortars M1064 and auxiliary vehicles, would be deployed at Novo Selo Training Area, the Bulgarian Defense Ministry said in a statement.

Novo Selo Training Area, one of the largest military bases in Bulgaria, is one of the four joint U.S.-Bulgarian military facilities in the Balkan country.

Bulgaria, a NATO member since 2004, signed a defense cooperation agreement with the United States in 2006.

According to the agreement, the United States may deploy defense equipment and no more than 2,500 personnel to the Novo Selo Training Range, the Aytos Storage facility, Bezmer Air Base, and Graf Ignatievo Air Base, and use these facilities for activities such as security cooperation exercises, refueling of aircraft, and temporary maintenance of vehicles.