The surrounding issue has been very much in the news recently.
When the update to the International Broadcast part of WRTH was published I was startled to see the new 400kW transmitter at Phước Dinh operating on 1071kHz mentioned there. The town is on the East coast of the country.
Asiawaves has the details of the VOV5 broadcasts in English and Mandarin.
The clue is in mention of that language.
In short, the Chinese have been sending their huge navy all over the South China Sea.
The Spratly islands have no less than 4 nations claiming bits of it. Vietnam has control over the main island called Spratly.
Therefore VOV5 is sending out the signal at 135 degrees to “persuade” Chinese sailors not to over step their activities. Also the idea is to serve Vietnamese civilians in those far flung islands.
Fascinating stuff hopefully to explain an unusual use of a transmitter.

Dan Goldfarb, mwmasts iog (2023-05-21)