Viet Cong forces overrun Cai Be, the capital of Dinh Tuong Province, killing 11 South Vietnamese militiamen, 10 women, and 30 children. On July 31, South Vietnam charged that the enemy troops involved in the attack were North Vietnamese Army regulars and that Chinese communist advisors led the attack. This claim was never verified, but it is likely that North Vietnamese regulars participated in the action. This incident and numerous intelligence reports indicated that North Vietnamese regular troops were moving down the Ho Chi Minh Trail in great numbers to join the fighting in South Vietnam. This marked a major change in the tempo and scope of the war in South Vietnam and resulted in President Lyndon B. Johnson committing U.S. combat troops. North Vietnamese forces and U.S. troops clashed for the first time in November 1965, when units from the newly arrived 1st Cavalry Division engaged several North Vietnamese regiments in the Battle of the Ia Drang Valley in the Central Highlands.