"Agreed, I would expect the base(s) in the region to be on some escalated level of alert as soon as the plane went missing in "9-11" style transponders off. Like a disturbed wasps nest some interceptors would be up and anchored navy ships put to sea. Based on past events if it showed up on defense radar they would have at least 2 interceptors."
Agree and all relevant data would be sent to threat assessment. First piece TSPX ceases to respond between goodnight KL and hello HCM -TA personnel do not believe in coincidence, threat level goes up, available spook sats are tasked to locate a commair traveling sans ident. If they learn the bird turned left to 263, threat level is up another notch and if they pick up on the second turn (and especially if they pick up even a suspicion of an attempt to shadow another plane) the code red alarm bell goes off -need we draw pictures as to where they would go from here...