Mullen, the US Chairman of the Joint Chiefs of Staff, told CBS news in an interview on Sunday that the Western military operation could end in a stalemate with longtime Libyan ruler Muammar Gaddafi.
The top military commander added that the end-game of military action in Libya was “very uncertain.”
The remarks come as US and European forces have unleashed airstrikes and cruise missile attacks against forces loyal to Colonel Gaddafi.
Mullen also noted that military mission has a clear, limited scope. He also could not predict how long the action might take or what its outcome might be.
The remarks come as US and European forces have unleashed massive airstrikes and cruise missile attacks on oil-rich Libya. France initiated the war hours before US and UK warships and submarines joined in.
Missiles are reported to have hit the Tripoli airport and targeted in the western city of Misratah. Nineteen US planes, including three B2 stealth bombers, took part in a dawn raid.
Scores of people, many of them civilians, were killed in the attacks.
China, Russia, Arab League and the African union have condemned the strikes.
It is the biggest Western military intervention in the Arab world since the 2003 invasion of Iraq.
Experts say main motive behind the western allies’ attack is the vast oil reserves in the North African country.