PRAGUE (Xinhua) -- U.S. experts again examined the conditions of the possible radar base in the Brdy military district of the Czech republic, Defense Minister Vlasta Parkanova said.

The U.S. experts studied local hydrology and geology, the quality of infrastructure and accessibility, CTK reported.

Czech Defense Ministry spokesman Andrej Cirtek said that the U.S. team comprises mainly of civilians, and only four soldiers.

The group is headed by Julian Savage, from the U.S. Missile Defense Agency (MDA), who reportedly also headed the U.S. team in April.

In early April, first group of five U.S. experts already visited the Brdy military district to examine all the sources of broadcast such as radio, television and other radar installations that could influence the military radar base. They also visited the meteorological radar in Brdy and met representatives of the Czech telecommunications Office that issues broadcasting licenses.

The United States unveiled its plan in January to place a radar system in the Czech Republic and 10 interceptor missiles in Poland, as components of the missile shield.

The USA and the Czech republic started last week the first round of official negotiations on the radar system that is to be part of the U.S. missile shield.