The United States is not ruling out the use of military force to free 21 South Korean hostages held by the Taliban in Afghanistan, a senior State Department official said Thursday. "All pressures need to be applied to the Taliban to get them to release these hostages," said Richard Boucher, assistant secretary of state for South and Central Asia. "We hope that pressure can be effective in a variety of ways, the goal is to get these people released unharmed, to get them released peacefully and safely." "We will all make efforts together to try to encourage that," he told reporters at the State Department, referring to close cooperation between the governments of the United States, Afghanistan and South Korea to win the hostages' release. He declined to elaborate on what pressure or efforts were now being used to convince the Taliban to let the South Koreans go but said they included the option of military force.