Iran-backed Yemeni fighters launched drone strikes on the United Arab Emirates that caused explosions and a deadly fire outside the capital, Abu Dhabi, ratcheting up security risks in the major oil-exporting region at a critical time.

One of the biggest attacks to date on UAE soil ignited a fire at Abu Dhabi’s main international airport on Monday and set fuel tanker trucks ablaze in a nearby industrial area. It took place days after Yemen’s Houthi fighters warned Abu Dhabi against intensifying its air campaign against them.

Crude extended gains to the highest level in seven years on Tuesday after the assaults in the UAE, OPEC’s third biggest oil producer.