Internet reports that Iran's retaliatory strike on the U.S. base in Qatar was not as severe as investors feared, easing market concerns that the conflict would immediately interrupt supplies in the Middle East, and oil prices fell. U.S. oil plunged 4% after Iran fired a missile at a U.S. base in Qatar. Traders had feared Iran's retaliatory response would involve closing the Strait of Hormuz, through which about a fifth of the world's oil passes. Although there were initial fears that Iran would disrupt supplies in retaliation for the United States, those fears have waned. "It seemed to me that it was carefully planned, with Iran attacking an empty U.S. base, issuing numerous advance warnings, closing airspace, and providing guidance for evasion." "Iran responded with face and stayed away from the Strait of Hormuz," said Harry Tchilinguirian, head of research at Onyx Capital Group.