The Pentagon announced on Friday it was bolstering US forces in Saudi Arabia after Riyadh asked for reinforcements following the September 14 drone-and-missile attack on Saudi oil plants which Washington blames on Iran.

Defense Secretary Mark Esper said that two fighter squadrons and additional missile defense batteries were being sent to Saudi Arabia, for a total of about 3,000 new troops from September this year.

The move comes as tensions jumped Friday after Tehran said that suspected missiles had struck an Iranian tanker in the Red Sea off the coast of Jeddah, Saudi Arabia.

Tehran did not blame arch-rival Riyadh for the attack, and US defense officials said they were still looking into it and had no immediate explanation.