Obama Nominates Pentagon Veteran Ashton Carter as Defense Secretary

President Barack Obama on Friday nominated Ashton Carter to be his fourth defense secretary, elevating a Pentagon veteran to lead the nation’s military as it faces growing conflict in the Middle East.

Should he be confirmed by the Senate, Mr. Carter would take over a Defense Department constrained by slimmer budgets that could make it harder to combat global threats, from Islamic State fighters trying to carve out an extremist enclave in the Middle East to Russian forces testing the fortitude of the North Atlantic Treaty Organization.

Mr. Carter would...