U.S. crude oil prices fell over 6% on Monday, marking their worst day in more than two years, after Israeli strikes on Iranian military facilities left Iran’s energy infrastructure unscathed.

West Texas Intermediate futures dropped 6.13% to $67.38 per barrel, while Brent futures fell 6.09% to $71.42 per barrel.

The Israeli attacks, in response to Iranian missile launches, reportedly caused limited damage, with Iran’s oil operations continuing normally, CBS News has reported.

Markets had been anticipating potential disruptions to Iranian oil supplies, which account for about 4% of global output, as tensions in the Middle East escalate following recent conflicts.

Written by B.C. Begley