Secretary of State Marco Rubio lost his cool at a G7 foreign ministers meeting Friday after the European Union's top diplomat publicly called him out over the Trump administration's failure to pressure Russia over Ukraine — then lied to reporters about it afterward, according to a report that cited sources who witnessed the exchange.EU foreign policy chief Kaja Kallas, a prominent Russia hawk and former Estonian prime minister, turned to Rubio during a discussion of Ukraine and reminded him of a promise he had made at the same forum a year earlier that the U.S. would run out of patience and take stronger steps against Moscow if Russia obstructed peace efforts."A year has passed and Russia hasn't moved," Kallas told Rubio, according to three sources who attended the meeting. "When is your patience going to run out?"Rubio, visibly annoyed, fired back."We are doing the best we can to end the war," he shot back, raising his voice. "If you think you can do it better, go ahead. We will step aside."Several European ministers in the room intervened to urge the U.S. to stay engaged in Russia-Ukraine diplomacy. Rubio and Kallas later held a brief private conversation to cool tensions, two sources said.Then Rubio walked out and told reporters none of it happened."These meetings are oftentimes about thanking America for the role we played... and appreciation for the mediating role we've tried to play in this war between Russia and Ukraine," he said. "No one there screams or raises their voices or says anything negative."The State Department called it "a frank exchange of views."