A new war of words ignited between President Obama and Russian President Vladimir Putin after a forceful Obama reiterated the United States' firm commitment to the NATO alliance and its intolerance of any Russian aggression in Ukraine.
"We will not accept Russia's occupation of Crimea or its violation of Ukraine's sovereignty. Our free nations will stand united so that further Russian provocations will only mean more isolation and costs for Russia," Obama said Wednesday in Warsaw.
Putin, meanwhile, accused America of being the real aggressor in its implementation of its foreign policy goals.
"It's clear that the United States is pursuing the most aggressive and toughest policy to defend their own interests - at least, this is how the American leaders see it - and they do it persistently," Putin said, according to an English transcript of an interview posted on the Kremlin’s website.
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"There are basically no Russian troops abroad while U.S. troops are everywhere," he added.
Later on Wednesday, Obama flew to Brussels where he is meeting with leaders from the Group of Seven nations. Putin was excluded from the summit, which used to be known as the G8 group of wealthy nations.
The leaders of the United States, Canada, Japan, Britain, France, Germany and Italy urged Russia in a joint statement on Wednesday to recognize the results of Ukraine's May 25 presidential elections and withdraw its troops on the Ukrainian border.
We are united in condemning the Russian Federation's continuing violation of the sovereignty and territorial integrity of Ukraine. Russia's illegal annexation of Crimea, and actions to de-stabilize eastern Ukraine are unacceptable and must stop. These actions violate fundamental principles of international law and should be a concern for all nations. We urge the Russian Federation to recognize the results of the election, complete the withdrawal of its military forces on the border with Ukraine, stop the flow of weapons and militants across the border and to exercise its influence among armed separatists to lay down their weapons and renounce violence. We call on the Russian Federation to meet the commitments it made in the Geneva Joint Statement and cooperate with the government of Ukraine as it implements its plans for promoting peace, unity and reform.
Obama's trip to Europe will culminate with the 70th anniversary of the D-Day landings in France on Friday. Putin is expected to attend the ceremony.
President Obama also met with Ukraine's President-elect Petro Poroshenko. Obama pledged $5 million in non-lethal aid to Ukraine and promised to seek congressional support for $1 billion to increase U.S. military presence in Europe.
Meanwhile, in Ukraine, pro-Russian separatists took control of a Ukrainian post in the country's eastern region of Luhansk.