Sergey Lavrov

A Russian policeman stands in front of an entrance to the U.S. Embassy in downtown Moscow in 2013. Ivan Sekretarev/AP hide caption

President Trump gestures to Russia's ambassador to the U.S., Sergey Kislyak, as he speaks to Russian Foreign Minister Sergey Lavrov in the Oval Office on Wednesday. Alexander Shcherbak/TASS/Getty Images hide caption

Secretary of State Rex Tillerson shakes hands with Russian Foreign Minister Sergey Lavrov at the start of their meeting in Moscow. Russia has accused the U.S. of breaking international law with its missile strike on Syria last week. Alexander Nemenov/AFP/Getty Images hide caption

Russian Foreign Minister Sergey Lavrov (left) and U.S. Secretary of State John Kerry (right) enter a news conference room Friday in Geneva to announce a cease-fire agreement for Syria. Fabrice Coffrini/AFP/Getty Images hide caption

President Obama and other leaders met in The Hague. Clockwise from bottom left: European Union Council President Herman Van Rompuy, Canadian Prime Minister Stephen Harper, French President Francois Hollande, British Prime Minister David Cameron, Obama, German Chancellor Angela Merkel, Japanese Prime Minister Shinzo Abe, Italian Prime Minister Matteo Renzi and EU President Jose Manuel Barroso. Sean Gallup/Getty Images hide caption

Russian Foreign Minister Sergei Lavrov, left, and U.S. Secretary of State John Kerry before their talks Friday in London. Afterward, they reported no breakthroughs on finding a solution to the crisis in Ukraine. Brendan Smialowski/AP hide caption

U.S. Secretary of State John Kerry during his testimony Thursday before a Senate Appropriations subcommittee. Michael Reynolds /EPA/Landov hide caption

Armed men in unmarked military uniforms — who witnesses believe are Russian troops, but who Russian leaders say are "local self-defense" forces — stand outside the territory of a Ukrainian military unit in the Crimean village of Perevalnoye. Maxim Shipenkov /EPA/Landov hide caption