 Though initial attacks stunned both the US and South Vietnamese armies , causing them to temporarily lose control of several cities , they quickly regrouped , beat back the attacks , and inflicted heavy casualties on North Vietnamese forces . During the Battle of Huế , intense fighting lasted for a month , resulting in the destruction of the city by US forces . During their occupation , the North Vietnamese executed thousands of people in the Massacre at Huế . Around the US combat base at Khe Sanh fighting continued for two more months . Although the offensive was a military defeat for North Vietnam , it had a profound effect on the US government and shocked the US public , which had been led to believe by its political and military leaders that the North Vietnamese were being defeated and incapable of launching such an ambitious military operation . U.S. public support for the war declined and the U.S. sought negotiations to end the war . 
