Thailand is well armed – but against whom or what, precisely?

Your front-page story notes that spending on defence has gone up dramatically under the junta government. While we must accept that all nations need to be prepared for the unexpected, is there any evidence of an outside threat to Thailand?
While there have been odd quarrels with the neighbours over the years, things appear to be fairly stable along Thailand’s borders.
Of course, there is the insurgency in the South that ebbs and flows, but does it justify such a massive increase in spending, particularly the purchase of heavy weapons and sophisticated aircraft?
We know there are some in the defence forces who are interested in big boys’ toys, such as blimps and submarines that are not actually fit for purpose, so it may just be more of the same there.
But the question must be asked: If the military is buying more weapons, against whom does it intend to use them? 
Brian D