Unrelenting Iranian attacks on shipping traffic and energy infrastructure pushed oil above $100 a barrel Thursday, as American and Israeli strikes pounded the Islamic Republic with no sign of an end to the war in sight.

The ongoing American-Israeli war with Iran, for all its complexity and global effects, boils down to a single question: Who can take the pain the longest? A surge in oil prices points to what may be Iran’s most effective weapon and the United States’ biggest vulnerability in continuing the campaign: Damaging the world economy.

Iran might be outgunned and outspent by the US and Israel but it has one major advantage — its control over the Strait of Hormuz.

The US and Israel’s war on Iran forced world governments to intervene to shore up energy supplies, even as President Donald Trump once again said fighting will end soon.

Iran targeted the world’s busiest international airport Wednesday and attacked commercial ships as U.S. and Israeli strikes rocked Tehran, while the United Nations' most powerful body demanded a halt to the Islamic Republic’s strikes on its Gulf neighbors that threaten global oil supplies.

The price of Brent crude oil, the international standard, spiked back over $100 as Iranian strikes hit ships in the regions waters and the ongoing American-Israeli war with Iran showed so signs of slowing.

The ongoing American-Israeli war with Iran, for all its complexity and global effects, boils down to a single question: Who can take the pain the longest? A surge in oil prices points to what may be Iran’s most effective weapon and the United States’ biggest vulnerability in continuing the campaign: Damaging the world economy.

The IEA said Wednesday that its 32 member countries would release 400 million barrels of oil from emergency reserves.