A cease-fire goes into effect at 8 a.m., Saigon time (midnight on January 27, Greenwich Mean Time).
When the cease-fire went into effect, Saigon controlled about 75 percent of South Vietnam's territory and 85 percent of the population. The South Vietnamese Army was well equipped via last-minute deliveries of U.S. weapons and continued to receive U.S. aid after the cease-fire. The CIA estimated North Vietnamese presence in the South at 145,000 men, about the same as the previous year. The cease-fire began on time, but both sides violated it. South Vietnamese forces continued to take back villages occupied by communists in the two days before the cease-fire deadline and the communists tried to capture additional territory.
Each side held that military operations were justified by the other side's violations of the cease-fire. What resulted was an almost endless chain of retaliations. During the period between the initiation of the cease-fire and the end of 1973, there were an average of 2,980 combat incidents per month in South Vietnam. Most of these were low-intensity harassing attacks designed to wear down the South Vietnamese forces, but the North Vietnamese intensified their efforts in the Central Highlands in September when they attacked government positions with tanks west of Pleiku. As a result of these post-cease-fire actions, about 25,000 South Vietnamese were killed in battle in 1973, while communist losses in South Vietnam were estimated at 45,000.