U.S. officials on Wednesday warned against escalating tensions between Turkey and Iraq, renewing calls for restraint by both sides as Turkish warplanes bombed Kurdish rebel bases on the Turkish side of the Iraqi border. “We are concerned about the continuing skirmishes that are happening up there, and terrorist attacks that are being launched by the PKK (Kurdistan Workers Party) against the Turks,” White House spokeswoman Dana Perino said. “We continue to urge both sides to exercise restraint-meaning the Iraqis and the Turks-in terms of escalating tensions between the two countries,” Perino told reporters. Turkish warplanes on Wednesday bombed Kurdish rebel targets along the Iraqi border in southeast Turkey, the country's semi-official Anatolia news agency reported. Asked whether Washington viewed Turkish airstrikes along the Turkey-Iraq border as an escalation of the conflict, Perino replied, “I have not heard it characterized in that way.” Secretary of State Condoleezza Rice on Wednesday said Washington hoped that both sides would find a way to defuse tensions. “We have encouraged several things. One is that the Iraqis and the Turks should make extraordinary efforts [together],” she told a congressional panel. Rice welcomed the Iraqi government's announcement that it is closing down PKK offices and acting to prevent the cross-border movement of rebel fighters. “It's very difficult because these people are in very remote areas of Iraqi Kurdistan, but that is not an excuse,” she told the House of Representatives Foreign Relations Committee.