Unidentified Vietnamese Flags

Recently there was a short report in TV about the trip of an US war ship to the river that goes to Ho Chi Minh city. The ship was escorted by a Vietnamese war ship (small like a coast guard or so) bearing a flag in the prow, and the national flag in the mast at center (no flag in the stern) The flag in prow was greenish and yellow horizontal (2:1) in proportion c. 2:3 In the green part were an arms, perhaps the national arms, army emblem or other, probably multicoloured.
Jaume Ollé,19 November 2003