It was the middle of the night.

Most countries do not have fighter pilots on alert, ready to scramble. At least, the US hasn't since about the late 1970s/early 80s, with the exception of post 9-11. I think this has mostly been ended for money. So who has the capability in southeast Asia? China? Maybe on alert, but same limitations at night. If they went southwest? No country with the hardware or money to do this 24/365, really.

Sporadic, if any, radar hits. Launch a jet, or let him sleep?

And if you intercept at night, what do you do? Look at navigation lights? Look at them on NOGs? ( Night Observation Goggles). Call them on 121.5? What if they don't do anything? Shoot down a plane flying straight and level in international airspace?

The last time this was done was when the Russians shot down KAL 007, but they had been tracking an RC-135 that they knew was regularly just off the east coast of Russia, listening and recording. They mixed-up the plots, and followed the wrong plane...a plane that made a 1-degree INS input error, putting them 60 miles inside Russia. (But not when they were shot down).