During the 2004 Ukrainian presidential election, Putin twice visited Ukraine before the election to show his support for Ukrainian Prime Minister Viktor Yanukovych, who was widely seen as a pro-Kremlin candidate, and he congratulated him on his anticipated victory before the official election returns had been in. Putin's personal support for Yanukovych was criticized as unwarranted interference in the affairs of a sovereign state ("See also The Orange revolution"). According to a document uncovered during the United States diplomatic cables leak Putin “implicitly challenged" the territorial integrity of Ukraine at the April 4, 2008, NATO-Russia Council Summit in Bucharest, Romania.