BAGHDAD, Iraq – Iraq’s interim prime minister on Sunday warned that efforts to resolve the standoff in Fallujah peacefully have entered their “final phase” and said he will not hesitate to launch “a military solution” to end Sunni insurgents’ hold over the city.

In another city of Iraq’s stormy Sunni Triangle, a rocket slammed into the Sunubar Hotel in Tikrit late Sunday, killing 15 Iraqis and wounding eight others, hospital officials said. Insurgents may have been aiming at an American position, which was targeted by a second rocket. U.S. officials said no American casualties were reported.

Prime Minister Ayad Allawi warned of civilian casualties, saying that if he orders an assault it would be with a “heavy heart,” because “there will be some loss of innocent lives.”

“But I owe, owe it to the Iraqi people to defend them from the violence and the terrorists and insurgents,” he said.

U.S. officials say Allawi will personally issue the final order to launch any all-out assault on Fallujah and other Sunni insurgent strongholds north and west of the capital.

U.S. and Iraqi commanders want to put down guerrillas before vital elections due to be held by Jan. 31. On Sunday, insurgents in Fallujah fired mortar rounds and rockets at U.S. Marines, who responded with artillery. U.S. aircraft also struck suspected rebel positions, Marine officials said.

Clashes were also reported between U.S. forces and insurgents in Ramadi, west of Fallujah, killing seven Iraqis and injuring 11, hospital officials said.

Allawi also said authorities have arrested 167 Arab foreign fighters, who are in Iraq’s custody. He said the government had identified financiers abroad and would ask other Arab governments to send them back for prosecution.

The blast in Tikrit, 80 miles north of Baghdad, sent frightened guests of the three-story hotel running into the street, some barefoot, others with bloodstains on their clothes.

U.S. military officials blamed the attack on “anti-Iraqi forces,” the term they use for insurgents. They said two rockets were fired, one of which exploded near an American military position but caused no damage or casualties.