Oil prices surged past $90 a barrel Monday after the United States and Iran exchanged direct military strikes, sending crude markets into their sharpest single-session rally in years.

Brent crude climbed more than 7 percent at the open as traders priced in the risk of sustained conflict near the Strait of Hormuz, the chokepoint through which roughly 20 percent of global oil supply passes.

Sources familiar with the situation told the Wail that back-channel negotiations between Washington and Tehran had not collapsed, a detail that trimmed some early gains by midday but left prices well above Friday's close.

The exchange of strikes, which the Wail confirmed through U.S. defense and Iranian state media reporting, is the most direct military confrontation between the two governments in years.

Analysts at three major energy trading desks told the Wail that a sustained blockade or mining of Hormuz shipping lanes could push Brent toward $120. No such action had been confirmed as of Monday afternoon.

The White House and Pentagon had not issued a coordinated public statement on the scope or duration of the strikes as of press time.

Congressional leadership on both the House and Senate armed services committees is expected to receive classified briefings Tuesday morning.