Oil Topples $100 as Iran-U.S. Conflict Reignites Inflation Fears

U.S. stock index futures slipped on Wednesday, pointing to another negative session for Wall Street's holiday-shortened week.

The global oil benchmark Brent topped $100 a barrel for the first time in about three-and-a-half months, while investors grew cautious ahead of key U.S. inflation reports that could solidify expectations for a Federal Reserve rate hike later this month.

The was last up 2.9% to $100.79 a barrel, as oil prices remained one of the main concerns for investors.

A string of attacks in the Middle East has intensified fears of a prolonged conflict between Iran and the U.S., with both sides exchanging more strikes. Speaking during a visit to Colombia, U.S. Secretary of State Marco Rubio indicated that the tit-for-tat strikes are unlikely to cease soon, warning Iran that it will 'lose tankers' when it tries to 'hit U.S. naval ships.'

The surge in oil prices has revived fears that higher energy costs could keep inflation elevated and persuade central banks to tighten policy.