Baghdad and foreign oil companies at work in Iraq’s giant oilfields are adopting extra security measures in anticipation of retaliatory attacks if the United States strikes neighboring Syria, industry sources said.

Car bombs and other attacks in recent weeks have led to the deaths of hundreds of Iraqis as the civil war in neighboring Syria aggravates deep-rooted sectarian divisions.

So far the violence in Iraq has not hit the operations of companies such as Exxon Mobil, BP, Eni and Royal Dutch Shell or deterred them from increasing oil output and turning Iraq into OPEC’s second-biggest producer.

Since 2010, these companies have been reviving the southern fields near the oil hub of Basra, helping raise output by 600,000 barrels per day (bpd) to 3 million bpd, and they want to carry on expanding output without incident. As U.S. President Barack Obama prepares for limited strikes against Syrian President Bashar al-Assad’s forces, Iraq’s South Oil Co (SOC), which oversees operations around Basra, has warned Western oilmen to restrict their movements.

“After the fears of the Syria strike, we have notified all foreign companies: British, American and others, to reduce their movements inside the city,” an SOC source said.