You overlook the primary role that Congress plays when it comes to the Federal Budget....the President only gets too spend the money Congress appropriates.
The Congress declares War....not the President.
Congress has created the War Powers act that allows for a more flexible authority for the President when it comes to use of military force.
I cited Obama....as a reference to the time period the Sequestration Act took place....and of course his inability to convince Congress to perform its primary task of crafting an Annual Budget for the Federal Government.
Congress is also very happy to continue deficit spending and thereby creating a tremendous Federal Debt that shall one day become. a very real and disastrous problem.