US Secretary of State Condoleezza Rice signed Tuesday what she called a landmark missile defence deal with the Czech Republic that drew immediate threats of a military response from Russia.

The accord permits the siting of a tracking radar station on Czech soil as part of an extended US missile shield that Washington says is necessary to ward off potential attacks by so-called "rogue" states such as Iran.

But Moscow immediately threatened to respond with "military resources" to what it sees as a threat on its doorstep from the proposed system.

"If a US strategic anti-missile shield is deployed near our borders, we will be forced to react not in a diplomatic fashion but with military resources," a statement from the foreign ministry said.

"It's truly a landmark agreement," Rice said after signing the accord with Czech Foreign Minister Karel Schwarzenberg. "It is an agreement that is befitting for friends and allies who face a common threat in the 21st century."

During her talks in Prague, Rice charged that Iran's work to build longer-range missiles was proceeding "apace" while at the same time it was defying international calls to halt sensitive nuclear technology.

"Ballistic missile proliferation is not an imaginary threat," the top US diplomat warned.

Rice also reiterated Washington's position that the radar station was not aimed at Russia and instead served as a "building block" for not just Czech and US security but for the "international community as a whole."

The United States wants the radar twinned with interceptor missiles in neighbouring Poland, although negotiations with Warsaw have becomed bogged down with Polish demands for additional security guarantees.

Rice said she thought it made no sense to visit Poland during her current tour of Europe because gaps remained in the negotiations.

Russian President Dmitry Medvedev had already clashed with US President George W. Bush over missile defence at their first face-to-face meeting, during a G8 summit in Japan on Monday.

Analysts say the Russians fear not only a potential long-term threat to their own nuclear deterrent and the security of their airspace but also associate the shield with NATO's enlargement to include Ukraine and Georgia.

NATO endorsed the US missile defence plan at its April summit in Bucharest.

The US has in the past suggested that Russian inspectors could visit the anti-missile sites, as long as Prague and Warsaw agreed.

"We want the system to be transparent to the Russians," Rice insisted Tuesday.

Protestors from Greenpeace who fear the missile shield will trigger a new arms race, unrolled a massive image of a target on one of the hills overlooking Prague ahead of Rice's arrival.

Opinion polls regularly show around two-thirds of Czech opposed to hosting the US radar.

Around 2,000 demonstrators gathered in Prague's central Wenceslas Square, with banners proclaiming "No to the Radar" and "Resign."

But Schwarzenberg expected the deal to be ratified by parliament.

"There are sufficient lawmakers who are sufficiently aware of their responsibility and will go forward in strength during the voting," he told reporters.

Czech Prime Minister Mirek Topolanek said the deal reflected a "joint desire to protect the free world".

Rice later told Czech television there will "be multiple states that will ultimately be involved in one way or another" in the shield, when asked if the United States sought to pressure Poland by hinting at using Lithuania as an alternate interceptor site.

"Lithuania is very interested and we're talking with those who are interested," Rice said according to an audio tape provided by the State Department. "Primarily we will continue to talk to Poles about this."

Rice admitted "there is still a long way to go in developing these (defence) systems," but said the US and the Czech Republic would jointly work on them and derive economic benefits from private sector involvement.

Prague was the first leg of a three-country tour that will take Rice to Bulgaria and Georgia where she will renew US support for Tbilisi's bid for NATO membership -- another bone of contention with Moscow.

She will also try to calm matters between Moscow and Tbilisi over the separatist Georgian regions of Abkhazia and South Ossetia. But she accused Moscow of fuelling tensions by failing to consult with Georgia over a presidential order offering Abkhazia direct relations.

earlier related report
Russia threatens to 'react' against US missile shield
Russia threatened Tuesday to react militarily if Washington erects defence installations on its Cold War turf, hours after US Secretary of State Condoleezza Rice signed a deal with the Czech Republic.

"If a US strategic anti-missile shield is deployed near our borders, we will be forced to react not in a diplomatic fashion but with military resources," a foreign office statement said.

"There is no doubt that the grouping of elements of the strategic US arsenal faced towards Russian territory" could lead Moscow to "take adequate measures to face the threats to its national security," it added.

The deal with Prague permits the siting of a tracking radar station and American troops on Czech soil.

It is part of an extended shield that Washington says is necessary to ward off potential attacks by so-called "rogue" states such as Iran.

The US also wants a radar system twinned with interceptor missiles in neighbouring Poland, although negotiations with Warsaw have becomed bogged down with Polish demands for additional security guarantees.

Former Soviet state Lithuania has offered itself as an alternative site should the Polish talks stall.

Russian President Dmitry Medvedev on Monday clashed with US President George W. Bush over missile defence at their first face-to-face meeting during the G8 summit in Japan.

"There are topics on which we are making progress, such as Iran and North Korea, there are topics on which we diverge, such as the missile shield and European matters, but there are possibilities for agreement," Medvedev said.

Analysts say Moscow fears not only a potential long-term threat to its own nuclear deterrent and the security of its airspace but that it is also wary given NATO's prospective enlargement to include the former Soviet states of Ukraine and Georgia.

NATO endorsed the US missile defence plan at its April summit in Bucharest.

The US has suggested Russian inspectors could visit the anti-missile sites, as long as Prague and Warsaw agreed.

Russia's Prime Minister Vladimir Putin said in February, when he was still president, that Moscow would point its missiles towards Ukraine, Poland and the Czech Republic if NATO enlargement or the proposed US missile shield got underway.

In July 2007, Moscow announced its intention to deploy missiles in the Kaliningrad enclave between Poland and Lithuania, if Washington did not accept a Russian remplacement to the anti-missile project.

Russia had at the time suggested the solution of sharing a radar base in Azerbaijan with the US. It reiterated this proposal for a joint Russia-NATO anti-missile shield on Tuesday.

"Our proposals to create a collective anti-missile defence system on the principle of equal security for all remain on the table," said a "highly-placed official from the Russian Ministry for Foreign Affairs," as cited by Interfax news agency.

earlier related report
Rice starts Europe tour with harsh words for Russia
US Secretary of State Condoleezza Rice arrived in Prague Tuesday to sign a missile defence deal opposed by Moscow and to warn Russia to stop allegedly stoking separatist tensions in Georgia.

Beginning a three-country European tour that will also take her to Georgia, Rice arrived to a backdrop of protesters who objected to the Czech government's decision to accept the siting of the US anti-missile radar system there.

"We have said both Georgia and Russia need to avoid provocative behaviour but frankly some of the things the Russians did over the last couple of months added to tension in the region," Rice said, citing Russia's failure to consult with Georgia over a presidential order offering Abkhazia direct relations with Russia.

"Georgia is an independent state. It has to be treated like one," she added.

Latent tensions between Tbilisi and Moscow over the separatist regions of both Abkhazia and South Ossetia have flared up over the last week.

"I want to make very clear that the US commitment to Georgia's territorial integrity is strong," the Secretary of State said.

Rice is due in Georgia late Wednesday as part of her three-country mini-tour, which will also take in Bulgaria.

In Tblisi, she will renew US support for Georgia's bid for NATO membership -- another bone of contention with Moscow -- and try to calm tensions over Abkhazia and South Ossetia.

Georgia regularly accuses Russia of seeking to annex South Ossetia and Abkhazia, and derail its efforts to join the NATO military alliance. Russia in turn accuses Tbilisi of preparing to take back the breakaway regions by force.

Rice said she would not be visiting Poland, where the US wants to install missile interceptors. The two countries have been unable to agree terms for the deal after 14 months of talks.

"There are remaining issues but the United States has made a very generous offer" to the Poles who want to improve their air defences, Rice said.

In Prague however, she will sign the agreement over siting a US missile defence radar system in the former Soviet-bloc country, a development that Moscow has fiercely opposed.

The United States wants to deploy the shield in the central European nations by 2011-2013 to ward off potential attacks by so-called "rogue" states such as Iran. Russia has denounced the plan as a threat to its own security.

NATO endorsed the US plan at its April summit in the Romanian capital Bucharest.

Concerning Russian anxiety about the anti-missile system in what used to be its backyard, Rice said Tuesday: "We want the system to be transparent to the Russians."

The US has in the past suggested that Russian inspectors could visit the anti-missile sites as long as Prague and Warsaw agreed.

Prague has objected to a permanent Russian presence for monitoring the radar's operations, which is what Moscow is seeking.

In Prague, protestors from Greenpeace unrolled a massive image of a target across the city's skyline Tuesday ahead Rice's arrival.

"Do not make a target of us," proclaimed the banner at Letna hill overlooking the Czech capital at the foot of a giant metronome erected by the artist Vratislav Novak in 1991 following the collapse of the communist regime.

Anti-rader actions have stepped up in recent months with a hunger strike by anti-base activists, occupation of the military site earmarked for the radar by Greenpeace members and demonstrations.

Polls regularly show around two-thirds of Czech opposed to hosting the US radar. A survey by the CVVM agency published this month showed 68 percent opposed to the US radar.