NEW YORK — A drop in oil prices on Monday helped send the U.S. stock market to its best day since the war in Iran began.

The S&P 500 climbed 1% for its biggest gain in five weeks. The Dow Jones Industrial Average added 387 points, or 0.8%, and the Nasdaq composite jumped 1.2%.

The driver for markets once again was the price of oil. A barrel of benchmark U.S. crude fell 5.3% to settle at $93.50, easing some pressure off the economy after topping $102 earlier in the morning. Brent crude, the international standard, fell 2.8% to $100.21 per barrel after earlier getting as high as $106.50.

It’s a reprieve, for now at least, after oil prices spiked from roughly $70 before the United States and Israel began their attacks on Iran. In response, Iran has nearly halted traffic through the narrow Strait of Hormuz, where a fifth of the world’s oil typically sails from the Persian Gulf to customers worldwide. That has oil producers cutting production because their crude has nowhere to go.

The worry in financial markets is that if the strait remains closed for a long time, it could keep enough oil off the market to drive inflation up to a debilitating level for the global economy.

President Donald Trump over the weekend demanded that other countries hurt by the closure of the Strait of Hormuz “take care of that passage” and said his country “will help — A LOT!”