FACTBOX-Proposed U.S. missile shield in E.Europe

                                
 July 8 (Reuters) - The United States and the Czech Republic
will sign a pact on Tuesday for the central European country to
host a radar system, part of U.S. plans to create a missile
defence shield in Europe.
                                
 The proposed shield, which also envisions up to 10
interceptor missiles in Poland, is meant to defend against what
Washington says is the potential threat of a missile attack from
Iran against European and U.S. targets.
                                
 The project needs approval in Poland and faces a tough
parliamentary ratification process in the Czech Republic, where
more than two thirds of the public oppose the plan. Russia is 
opposed to it and says it will threaten its security.
                                
 Following are some details about the proposed missile
shield.
                                
 
                                
 THE PERCEIVED THREAT
                                
 * General Henry Obering, head of the Pentagon's Missile
Defence Agency (MDA), has said U.S. intelligence suggests that
by 2015, Iran could follow North Korea's example and develop a
long-range missile capable of striking the United Sates.
                                
 * The United States brought an earlier anti-missile
umbrella, based in Alaska and California, on line in 2004 to
protect against the perceived North Korean threat. The Czech and
Polish sites would augment that system.
                                
 * Washington has tried to quell concerns in Moscow that the
system would pose a threat to Russia by highlighting that the
shield's missiles are defensive only -- carrying no warheads --
and would be no match for Russia's nuclear arsenal.
                                
 
                                
 THE TECHNOLOGY
                                
 * The proposed $3.5 billion system would use "hit-to-kill"
technology in which an array of sensors and radar would detect
an enemy missile in flight and guide a ground-based interceptor
to destroy it.
                                
 * Without using explosives, the interceptor would ram an
incoming warhead at a closing speed of 15,000 miles per hour
(24,000 kph) in a process likened to hitting a bullet with
another bullet in space.
                                
 * The MDA says tests show the technology is sound. But
critics, including the Washington-based Centre for Defense
Information, say the evidence is misleading, many tests were
made in controlled circumstances not resembling real attacks,
and more results are needed to prove the system works.
                                
 
                                
 THE PLAN
                                
 * The radar installation planned for the Czech Republic
would aim its coverage towards the Middle East to detect a
missile in flight and guide interceptor missiles into the
trajectory of the approaching warhead. 
                                
 * Washington has proposed placing as many as 10 interceptor
missiles with a range of up to 1,800 miles (3,000 km) in Poland,
The missiles would be housed in underground silos in an area
about the size of a football field. 
                                
 * Poland and the United States have reached a tentative deal
on installing the U.S. anti-missile base there, but Warsaw has
yet to fully agree and wants billions of dollars from the United
States to upgrade its air defence systems.
                                
 * If approved, construction on both sites could begin in
2009, and could begin functioning in 2011-2013.
 (Sources: U.S. Missile Defense Agency, Pentagon, Centre for
Defense Information)
 (Compiled by Michael Winfrey; Editing by Charles Dick)