By Missy Ryan
WASHINGTON (Reuters) - Western strikes on Libyan air defenses over the past two days had crippled Muammar Gaddafi's capability to launch airplanes and detect foreign aircraft, a senior U.S. military official said on Sunday.
"We judge these strikes to have been very effective in significantly degrading the regime's air defense capability," Vice Admiral Bill Gortney, director of the U.S. military's Joint Staff, told reporters at the Pentagon.
"There has been no new air activity by the regime and we have detected no radar emissions from any of the air defense sites targeted," Gortney said. "There has been a significant decrease in use of all Libyan air surveillance radars."
The strikes began on Saturday, as a coalition of Western nations vowed to prevent Gaddafi from launching attacks on civilians as he seeks to crush an uprising against his four-decade rule.
Gortney said Libya's declaration of a new ceasefire on Sunday was not credible.
"I question anything that Gaddafi calls for. He called a ceasefire and then told his troops to move into Benghazi after he called for a ceasefire," Gortney said.
As smoke was seen rising above Tripoli from the direction of Libya's presidential palace, Gortney said Gaddafi was not being targeted by coalition air strikes.
"We are not going after Gaddafi," Gortney said. "At this particular point, I can guarantee that he's not on a targeting list."
"If he happens to be in a place -- if he's inspecting a surface-to-air missile site and we don't have any idea that he's there or not, then yes. But no, we're not targeting his residences," he said.
Gortney, speaking after heavy anti-aircraft gunfire boomed across central Tripoli, said no coalition aircraft had been hit in operations over the past few days.
He also said the coalition acting against Gaddafi, which originally grouped the United States, Britain, France, Italy and Canada, had broadened to include Belgium and Qatar.
(Additional reporting by Lesley Wroughton, Caren Bohan and Todd Eastham; editing by Christopher Wilson)