Washington (CNN) -- Embattled Libyan strongman Moammar Gadhafi's forces have made significant strides against rebel fighters, as the United Nations is working quickly to pass a resolution authorizing international intervention, a senior State Department official told senators Thursday. In remarks to the Senate Foreign Relations Committee, William Burns, the undersecretary for political affairs at the State Department, said Gadhafi's forces are only about 160 kilometers (about 100 miles) outside of the rebel stronghold of Benghazi. "They've made advances taking full advantage of their overwhelming military superiority in military fire power," Burns said. Burns expressed fear that Gadhafi, now isolated by the world community, could turn to terrorism again.
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Gadhafi's forces have made significant advances against rebels, an official says
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The official briefs a Senate panel on the situation in Libya
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Senators express frustration with U.S. response to Gadhafi so far
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The U.N. Security Council is scheduled to vote Thursday on Libya
Senators, in turn, expressed frustration with the lack of progress by the United States in responding to @placeholder beyond sanctions and warnings, as the U.S. tries to build international consensus for any military intervention.