Having once upon a time been in the intercept/shoot em down business, I see this conversation about intercepts is getting into the very hypothetical unrealistic mode.
First off, most countries in peacetime do not establish alert conditions that require a prompt response from their interceptors. It is assumed that there will be intelligence received in sufficient time to increase the threat response level, We are talking days not hours of advance notice here. Then the alert level will be set based upon the perceived threat. Other than actual airborne alert status, the shortest practicable ground alert is 5 minutes with aircrew and line personnel continuously at the aircraft, but the engines not running.
If this level of alert is to be done continuously it requires either dedicated assets (bigger airforce) or surge tasking of existing interceptor units for a defined period. (expensive)
The next common level of alert would be 15 minute alert with the crews in a crew shack near the flight line. This requires almost the same level of assets, but is not so wearing on the personnel and so can be maintained longer.
Next level of alert would be several hours with designated personnel on call at home.
And finally, with no perceived threat, the intercept units would be in training mode, with all the vagaries of maintenance availability and individual levels of training affecting readiness.
It all comes down to tasking. What are the intercept units tasked to do by the leadership? Countries generally wish to keep their levels of readiness on a need to know basis.
I would personally be very surprised if any of the countries in the region had anyone in a short notice intercept role.
It is generally impractical in fuel requirements to chase down and intercept a subsonic target from the stern hemisphere beyond 50 nm range. It is also a technically challenging evolution, particularly at night, requiring a high level of training to assure success. If there was ever a desire to intercept MH370, it probably came too late to be implemented.