The White House partially nixed its longstanding embargo on lethal arms sales to Vietnam last year. So far, there's a major caveat: the weapons must be used for "maritime-related" defense. But some officials are pushing to kill the ban completely. 

US defense companies, with Washington's blessing, have been wooing the Vietnamese government for months. Now Washington itself is beefing up Vietnam's military. The US announced last month it would pour $119 million towards modernizing naval forces across Southeast Asia this financial year, with just under $20 million of that going toward boosting Vietnam's intelligence, surveillance and reconnaissance capabilities at sea.

To American GIs during the Vietnam War, supplying communist forces would have been unimaginable. Today, the idea isn't so shocking. The armed forces of the US and Vietnam are growing closer than ever thanks to a common goal: thwarting China's dominance in the hotly contested South China Sea.