Sri Lanka, Nov. 29 -- The USS Nimitz aircraft carrier is steaming back to the Persian Gulf region to provide backup for troops being pulled out of Iraq and Afghanistan.

It will be arriving in the Middle East days after Iran's top nuclear scientist was killed in an ambush that Tehran has blamed on Israel.

But the Pentagon said it was President Trump's withdrawal of troops of in the two countries that spurred the deployment of the aircraft carrier and its flotilla of ships back to the gulf, where it had been for much of the fall.

Iran's president has blamed Israel for the killing of a top nuclear scientist on Friday, and said it would not slow down the country's nuclear programme.

Hassan Rouhani also said Iran would retaliate over Mohse...