The Vietnamese have not had a coast guard very long, just two years, but it looks like after a recent visit by our Commandant, the US Coast Guard will be working more closely with them. The US had already committed to financing the purchase of US made patrol boats for the Vietnamese Coast Guard to the tune of $18M. We discussed this earlier here and here.
As you probably know, the Vietnamese and Chinese have an ongoing dispute over a large area of the South China Sea. A recent change has authorized the their Coast Guard to use force as necessary to expel those who violate law from Vietnamese waters.