Thats Voice of Vietnam. At that hour (5:00z) they are in Vietnamese from South Carolina (WHRI). Earlier they are from Wooferton. English service is:
1:00 - 1:30 via Wooferton UK
2:30 - 3:00 via Wooferton UK
3:30 - 4:00 via WHRI Cypress Creek South Carolina
in between the English program they do Spanish & Vietnamese.