New York. Oil prices plunged below $100 a barrel, and Asian markets and US stock futures jumped after the United States  and Iran agreed to a two-week ceasefire that includes the reopening of the Strait of Hormuz.

Futures for US crude oil sank 14.3% to $96.83 a barrel and Brent crude oil, the international standard, dropped 13.3% to $94.74. Oil prices had spiked because the war snarled the production and transportation of crude in the Persian Gulf. Much of that oil exits the gulf through the Strait of Hormuz to reach customers around the world, but Iran has blocked it to enemies.

Japan’s benchmark Nikkei 225 rose 4.8% and South Korea’s Kospi gained 5.6%. Futures for the S&P 500 advanced 2.3% as of 9:30 p.m. EDT, while Dow futures rose 2%.

Late Tuesday, Trump said he was holding off on his threatened attacks on Iranian bridges, power plants and other civilian targets. Iran’s foreign minister said passage through the strait would be allowed for the next two weeks under Iranian military management.

The dramatic moves in prices are just the latest swings to hit financial markets since late February because of constantly shifting signals about when the conflict may end. Even with word of a ceasefire, neither Iran nor the United States said when it would begin, and attacks took place in Israel, Iran and across the Gulf region early Wednesday.

Oil prices were shaky. The price for a barrel of benchmark US crude to be delivered in May briefly climbed above $117 before settling at $112.95.

The worry in markets has been that a long-term disruption will keep oil prices high for a long time and send a painful wave of inflation crashing through the global economy. Trump kept traders on edge by making a series of threats to blow up Iranian power plants, only to delay several times.

The average price for a gallon of regular gasoline across the United States has leaped to $4.14, according to AAA. It was below $3 a couple of days before the United States and Israel launched attacks to begin the war in late February.