U.S. Secretary of State Condoleezza Rice flies to Prague on Tuesday to sign a key treaty with the Czech Republic on construction of a missile defense radar in this eastern European country.

If ratified by Czech parliament, the treaty would represent a strategic move by Washington in Europe, analysts believe.

The treaty would mean the stationing of foreign troops in the Czech Republic for the first time since the Soviet invasion of 1968. The treaty will anger Russia, which says the U.S. system will undermine its security.

Washington says the missile shield, which includes interceptor missiles in neighboring Poland, is designed for the protection of most of its European allies from long-range missile threats from "rogue states" such as Iran.

The signing of the treaty is an important step. But hurdles to the U.S. plan remain as ratification of the treaty by the Czech parliament is not guaranteed.

The deal with the United States is opposed by the majority of Polish citizens. A recent survey revealed that two thirds of those polled do not support the plan. The major left-wing opposition party has decided to make people's voices heard and made it clear that it would not vote for the treaty in parliament. Several legislators from the ruling coalition have also expressed reservations.

Washington's negotiations with Poland have proven to be more difficult. On Monday, Polish Foreign Minister Radoslaw Sikorski met Rice in Washington hours before Rice's departure for Europe. But their efforts to strike a deal at the 11th hour failed. Warsaw has demanded billions of U.S. dollars in investment to upgrade its army, particularly air defenses.