During the Second Battle of Fallujah in 2004, U.S. Marines employed Molotov cocktails made with "one part liquid laundry detergent, two parts gas" while clearing houses "when contact is made in a house and the enemy must be burned out". The tactic "was developed in response to the enemy's tactics" of guerrilla warfare and particularly martyrdom tactics which often resulted in U.S. Marine casualties. The cocktail was a less expedient alternative to white phosphorus mortar rounds or propane tanks detonated with C4 (nicknamed the "House Guest"), all of which proved effective at burning out engaged enemy combatants.