“With the U.S. becoming involved, the risk of Iran retaliating by disrupting the flows of oil from the Middle East has risen significantly,” warned analysts at ANZ. “Prices in the $90–95/bbl range would be the likely outcome.”

Contracts for the S&P 500 declined around 0.3%. Global crude benchmark Brent jumped about 2.6% after surging as much as 5.7%. The dollar climbed against the euro and most major peers. Equity indexes in Japan and Australia fell less than 1% while Treasuries were little changed.

Oil prices jumped on Monday to their highest since January as the United States' weekend move to join Israel in attacking Iran's nuclear facilities stoked supply concerns. Brent crude futures were up 72 cents or 0.