Oh I think I know him well, however the Constitution and the law cannot be gotten around, he can wage War for 90 days then he needs approval from Congress, and he ain't getting it. And I would bet he knows to do so and have to pull out would be worse than not going at all. It would damage the Republicans on the world stage for many years to come.
Contrary to popular thought Presidents can't really do all the much. Especially when it come to spending money and such, that is the purview of Congress, more precisely the house.