The Hobo Woods by Eric Helm

After spending one year back in the World, U.S. Special Forces Captain Mack Gerber returns to Vietnam smack in the middle of a political boondoggle. Although the Americans have firm evidence of a major enemy buildup in the Hobo Woods region, they are advised to exercise extreme restraint against the NVA. This mandate is the result of a press-whipped U.S. administration buckling under severe antiwar sentiments. The ripple effect touches officers in the field in Vietnam, and they are cautioned to keep all missions low-profile. Mack Gerber is stunned at these new events, especially since the American military has now been allowed to shed its adviser role and openly take part in combat. Gerber can't believe his orders: Go look for the enemy, but don't find him!