Guerrilla fighters launched a massive attack on most and south vietna's thisattack called the was repelled. americans however were stunned that anenemy nearly defeated could__

The answer is as following:
A massive attack on most "American air bases" and south vietna's major cities.
This attack was called the Tet Offensive.
Anenemy nearly defeated could launch such a large-scale attack.

The Tet Offensive refers to an facilitated arrangement of north Vietnamese strike ahead more than 100 urban areas What's more outposts On south Vietnam. Those hostile might have been an endeavor should incite defiance Around the soutane Vietnamese number What's more sway those united states with scale back its contribution in the Vietnam War.