The United States had planned to halt combat missions and Tomahawk cruise missile launches at the weekend but accepted a NATO request to continue the operations for another 48 hours until Monday.
US combat sorties ended at 2200 GMT, with American warplanes on standby as NATO takes the lead, Pentagon spokesman Captain Darryn James said.
After that, "US aviation assets are expected to cease strike sorties and will remain on an alert status if NATO requests their support," James said in an email.
NATO had issued the request to extend US bombing raids after bad weather last week hampered combat flights, which military leaders said allowed Moamer Kadhafi's forces to advance.
Between 2200 GMT on Tuesday and 1000 GMT on Monday, US aircraft carried out at least two raids but launched no Tomahawk cruise missiles, James said.