TBILISI, Georgia (CNN)  -- Russia has likely moved additional troops into Georgia and its breakaway provinces over the past several days, several administration officials told CNN on Wednesday. The officials said Russia probably has at least 15,000 troops in the region. The U.S. government had estimated 8,000 to 10,000 Russian troops had moved into Georgia when fighting began last week. A Bush administration official stressed that the scope of Russia's military effort remains unclear. Russia was blasted diplomatically Wednesday by President Bush over reports of ongoing Russian military operations. U.S. Secretary of State Condoleezza Rice also said Russian military action in Georgia "must stop and must stop now."
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NEW: U.S. says Russian troops moved across border in past several days
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Bush warns Russia over reported cease-fire violations
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Georgia, Russia accuse each other of breaking the truce
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First U.S. humanitarian aid flight lands in Georgian capital
A @placeholder government spokesman said the soldiers "never had plans" to travel to the capital.