No, a single nuclear bomb on the Pentagon could start massive fires all along the East Coast. You are making the same error American strategists made during the Cold War.
There is a famous story from the 60s of what happened when those strategists computed how much firepower it should have taken to destroy Hiroshima. It came out saying that the nuke used there was 60 times too small to cause as much destruction as it actually did. After some research, they realized they werent adding the effects of fire to the calculation. Fire effects were added, and everything worked out.