Leadership in this interval leading up to inauguration is an informal collective of very competent people, who unfortunately lack the statutory authority on which all notions of deterrence rest.
The situation persists because the risk of domestic unrest is more real to the politically astute than the risk of hostile foreign powers.
A hostile foreign power might be emboldened to shortly take a risk we would normally call a miscalculation. Their numbers might actually add up.
The remedy to risk from hostile foreign powers is to reestablish the statutory authority that is the basis all forms deterrence, as provided for by the Constitution.
It’s much cheaper than fighting a war.