Verified Answer :

He launched Operation Linebacker.  He bombed Hanoi and Haiphong that led to the
destruction of the North’s economic and industrial centers.  He continued the bombings  and also threatened to withdraw U.S. and  end the agreement.  Nixon halted the bombings and signed the
Paris Peace Accord that ended U.S. involvement in the area.

B he ordered heavy bombing of Hanoi and Haiphong..