TBILISI, Georgia (CNN) -- The risk of a new era of east-west confrontation drew closer Saturday on the back of the conflict in Georgia and Russian anger over a U.S. deal with Poland to base part of its missile shield in the country.
U.S. Secretary of State Condoleezza Rice and Georgian President Mikheil Saakashvili announce the cease-fire.
1 of 2 more photos » It has been the toughest week in east-west relations since the end of the Cold War after Georgia launched an offensive against the Russian-allied separatist government in South Ossetia and Russia responded by invading, the conflict also spreading to a second breakaway region -- Abkhazia.
Then on Thursday the U.S. signed a preliminary deal to place part of its ballistic missile defense system in Poland, a plan that drew sharp objections from Russia. The interceptor rockets would be linked to an air-defense radar system in the Czech Republic.
Gen. Anatoly Nogovitsyn, a top Russian officer, said Friday that Poland's agreement to accept a battery of U.S. missile interceptors had put Poland at risk of attack, perhaps with nuclear weapons, The Associated Press reported.
Poland moved to diffuse the situation Saturday, saying it was open to Russian inspections of the missile interceptor base, AP reported. However, the Ukraine said it was interested in joining a joint missile defense system with other European countries.
Ukraine Foreign Ministry spokesman Liubov Abravitova would not specify if it was referring to the U.S. system.
Ukraine also warned Russia it may not allow its ships involved in blockading Georgian ports to return to Crimea bases it leases from Ukraine.
The U.S. maintains its missile shield is to deter rogue attacks from Iran, but Russia says it is aimed at it.
The level of rhetoric on both sides has grown louder through the week, U.S. President George W. Bush chiding Russia for Cold War-style behavior in its territorial conflict with Georgia, accusing it of "bullying and intimidation."
Russian President Dmitry Medvedev said Russia would "guarantee" peace in the Caucasus region but made no commitment to remove its forces from Georgia or its breakaway territories. Watch devastation in port of Poti »
"Peace needs to re-established in the region and guaranteed and underpinned so that no one again will get idiotic ideas, and this I see as the main task of the Russian Federation," Medvedev said.
Meanwhile U.S. Secretary of State Condoleezza Rice warned Russia that it had to withdraw its troops from Georgia after a cease-fire deal was signed by Georgian President Mikheil Saakashvili.
The office of French President Nicolas Sarkozy, who brokered the agreement, said Medvedev had confirmed Russia's cooperation.
"His country will sign a cease-fire accord with Georgia and scrupulously respect all agreements, including a troop withdrawal," Sarkozy's office said.
Fighting that started last week has died down in the region, but Russian forces remain.
Rice said international observers followed by neutral peacekeepers should be dispatched quickly to Georgia and its separatist regions of South Ossetia and Abkhazia, where Russia has a peacekeeping mission. Watch Rice demand Russia's withdrawal »
The conflict began late last week, when Georgia launched a military incursion into South Ossetia in an effort to rout separatist rebels.
Russia -- which supports the separatists, many of whom claim Russian citizenship -- has peacekeeping responsibilities for the region and responded by sending tanks into the province for what it said was peace enforcement. From there the violence spread into Georgia and Abkhazia. iReport.com: How is the Russia-Georgia conflict affecting you?
Under the cease-fire, about 1,500 Russian peacekeepers are allowed to remain inside, and can do patrols about 6 kilometers outside, the "zone of conflict," a reference to South Ossetia and Abkhazia.
They are not permitted to patrol in Gori and other Georgian cities and cannot hamper aid distribution or control ports, highways or railroads, the officials said. The limited exception for the Russian peacekeepers is allowed only until a more robust international peacekeeping force can be deployed. Watch President Bush on 'why Georgia matters' »
Analysts see the conflict in Georgia, which is seeking NATO and EU membership, as having wider international implications as Russia seeks to reduce Western influence on its doorstep.
Russian troops remained in control of two key Georgian cities despite pledges of a withdrawal. The Russians occupied the cities of Gori and Poti. Watch devastation in port of Poti »
International rights body Human Rights Watch on Friday accused Russia of dropping cluster bombs -- outlawed by more than 100 nations -- on Georgia, killing civilians. The claim was denied by Russian officials.
It is unclear how many people have been killed in the conflict, but various claims put the figure in the thousands. View a map of the region »
The U.N. High Commissioner for Refugees said Friday that it estimated that more than 118,000 people have been displaced by the fighting, citing statistics supplied by the Russian and Georgian governments.
About 30,000 people from South Ossetia fled to Russia, according to officials in the Russian region of North Ossetia, and up to 15,000 people from South Ossetia went south into Georgia proper, the Georgian government said.
Around 73,000 people in Georgia proper are displaced, including most of the population of Gori. A further 732 Georgians living in Abkhazia were evacuated from the remote Khodori Valley.
Rusland croses the bother of Gerogie and is heading towards the city.