American experts have completed a survey of potential sites in the Czech Republic for a strategic defence base.
The US wants to expand its missile defence system
During their week-long mission the 22 experts examined three military training grounds.
The US is considering building its first anti-missile base in Europe on the territory of either the Czech Republic, Hungary or Poland.
It will be designed to shoot down long-range missiles before they reach their targets in the US or Europe.
The US team told the Czech authorities that all three sites inspected were suitable for a future base, a Czech Defence Ministry spokesman, Jan Pejsek, told the BBC News website.
The issue is controversial in the Czech Republic. According to a recent opinion poll, quoted by the Associated Press news agency, a majority of Czechs oppose the plans for such a base.
The defence ministry official said the US experts' mission followed two years of talks between the two countries and was part of the security strategy adopted by the Czech government in 2004.
US experts have already been in Poland and are expected to go on a similar fact-finding visit in Hungary.
The base, designed to neutralise a missile attack on either the US or Europe, would employ up to 1,000 people, and though controversial, would bring substantial economic benefits to the host country.
Czech authorities stressed that the visit was purely technical, and any decision to set up an anti-missile base would be a political one.
However, the Czech Republic's chances of winning the contract for the base are being damaged by the ongoing political stalemate, BBC's Rob Cameron reports from Prague.
It is eight weeks since inconclusive parliamentary elections and there is still no new government in Prague. With a decision on the new base due in September, time is running out.