A newly inked deal allowing the U.S. to base a missile defense shield on Czech territory set off protests here and in Moscow, with the Russian government threatening that it may respond with military action.

Russian feathers were likely to get even more ruffled on Wednesday when Secretary of State Condoleezza Rice, who signed an initial missile agreement on Tuesday, begins a 17-hour visit to Georgia. The former Soviet state is in a violent standoff with Russia over a breakaway region called Abkhazia.

Rice and her Czech counterpart, Karel Schwarzenberg, signed the pact Tuesday to build a missile defense base near Prague as part of a U.S. global missile defense system aimed at countering possible threats from nations such as Iran. The deal is widely unpopular among Czechs, while Russia sees the system as a potential threat and a provocation in its old East Bloc sphere of influence.

Hundreds of Czechs gathered in a Prague downtown square to protest the agreement, waving banners with slogans such as "It's not over yet," and "Condoleezza is not welcome!"

The proposed U.S. missile defense system calls for a tracking radar in the Czech Republic and 10 interceptor missiles in Poland. Moscow has threatened to aim its own missiles at any eventual base in Poland or the Czech Republic.

Shortly after the treaty was signed, Russia's Foreign Ministry said Moscow would be forced to initiate a military response if the deal goes ahead.

If the agreement is ratified, "We will be forced to react not with diplomatic, but with military-technical methods," the Foreign Ministry statement said. It did not give specifics of what the response would entail. In February, then-President Vladimir Putin said that if the plan advances, Russia could aim missiles toward prospective missile defense sites and deploy missiles in the Baltic Sea region, which borders Poland.

President Bush discussed U.S. missile-defense plans with the new Russian president, Dmitry Medvedev, earlier this week during an economic conference of world leaders in northern Japan. Medvedev later told reporters that his hour-long chat with Bush yielded "no particular progress" on issues dividing the countries, particularly the missile shield.

White House national security spokesman Gordon Johndroe, with Bush in Japan, said early Wednesday: "As President Bush said to President Medvedev, we seek strategic cooperation on preventing missiles from rogue nations, like Iran, from threatening our friends and allies."

"We want to design a system between the United States, Russia and Europe, with everyone participating as equal partners," Johndroe added.

Rice has all but ruled out a stop in Poland this week to finalize plans for the missile defense shield. The plan is widely unpopular with the Polish public.

From Prague, Rice was making a brief visit to Bulgaria on Wednesday. She was to receive the nation's highest honor for her help in securing Libya's release of six medics nearly a year ago. Rice played less of a public role than several other international figures in winning the medics' release, but Libya agreed to free them in part to improve its relationship with the United States.

Rice had encouraged Libya to let the medics go, saying it was time that they returned to their families, but avoided strong public criticism of Libya over the case.

Bulgaria, home to five of the medics, also awarded the state medal to others involved in the release, including former French first lady Cecelia Sarkozy, who declined an invitation to accept it in person.

The five Bulgarian nurses and a Palestinian doctor were accused of infecting Libyan children with AIDS, charges that the United States and others called suspect at best.

The nurses and the doctor were arrested in 1999 and twice sentenced to death despite testimony from AIDS experts that the children — 50 of whom died — were infected by unhygienic conditions at the hospital.

They were released into Bulgarian custody last July after Libya and the EU struck a deal for millions of dollars in aid to Libya. Soon afterward a major deal was announced between European arms makers and Tripoli, and Libya is now negotiating a close to years of legal fights in the United States over its alleged support of terrorism.