Whether Trump is mentally unbalanced remains a moot point. Certainly his behaviour is erratic and dangerous. He also shows highly manipulative behaviour, which matches well a technique known as "gaslighting" as described in this article:



https://www.psychologytoday.com/blog/here-there-and-everywhere/201701/11-warning-signs-gaslighting



Whether mentally impaired or not the risk of war is very real and will only grow as it becomes Trump's only hope of distracting from the Russia enquiry. Much depends on the mid-term elections. So long as the GOP see him as an asset with their own voter base they are very unlikely to impeach him. But if the mid-terms deliver a rout for the Republicans we may yet see a President Pence, and the Democrats might then be in a position to clip the President's wings.