The war between the United States and Iran has upended the global oil market by severely disrupting the flow of oil through two critical waterways: the Strait of Hormuz and, in recent weeks, the Bab al-Mandeb Strait.

Iran is now stepping up attacks on tankers transiting Hormuz and the Persian Gulf, curtailing the volume of oil exiting the region and keeping global crude prices north of $100 a barrel.

There have been 12 reported attacks on vessels in or near Hormuz in the past week, according to the United Kingdom Maritime Trade Operations, which monitors maritime security in the region. And, earlier this week, two cargo ships sank after attacks by unknown projectiles in separate incidents.

Analysts say intensifying attacks by Iran are in response to the large quantities of oil that have managed to exit Hormuz in recent weeks. The US military has led an effective operation to ferry oil across the strait by assisting “dark” transits – tankers sailing with their transponders turned off and shuttling oil to ships waiting in the Gulf of Oman. Meanwhile, Iran continues to struggle to sail its own tankers through the waterway because of a US naval blockade.

The conflict, now in its eighth month, has also widened to include fighting between Saudi Arabia and Iran-backed Houthi militants in Yemen. The Houthis have targeted Saudi oil tankers transiting the Bab al-Mandeb Strait and, in recent days, launched deadly strikes on Riyadh’s main international airport. The crisis will have long-term ramifications on the global oil market, say analysts.

Oil-importing countries increasingly understand they must “structurally reduce their oil consumption” to become less vulnerable to external shocks, Georg Zachmann, a senior fellow at think tank Bruegel, told CNN.

That, alongside other measures, could help “shield (them) from this increasingly uncertain world,” he said.

The Bab al-Mandeb Strait became more strategically important after the war disrupted the neighboring Strait of Hormuz.

At its peak, around 4.5 million barrels of crude per day were exported from the Saudi Red Sea port of Yanbu, with the bulk – about 3 million barrels per day – exiting via Bab al-Mandeb, according to Richard Bronze, co-founder of Energy Aspects. But those flows “collapsed” after the Houthi threat started escalating this summer, he said.

Johannes Rauball, senior crude analyst at Kpler, said that if the Houthis begin threatening ships from all countries, “This would really create another blow for crude markets. It would really push prices higher again, really tighten balances.”But after an attack last month by drones from inside Iraq on Saudi Arabia’s East-West pipeline – which pumps crude toward the country’s Red Sea ports – Riyadh pivoted quickly, stepping up crude exports through the Strait of Hormuz via the US military-assisted shuttle operation.

US President Donald Trump said Iran was probably behind the September attack, with Iran-backed militia groups known to operate inside Iraq. Iran’s foreign ministry has “categorically denied” the accusation. The East-West pipeline is now back online, according to several reports.

Asian countries — the biggest buyers of Saudi oil — have borne the brunt of the crisis during the war, but they have adapted by cutting consumption. China has also greatly reduced its imports by tapping into its strategic reserves. The crisis has also pushed some Middle Eastern countries to explore new export routes through yet-to-be-built pipelines.

“The longer this conflict drags on, the less leverage Iran actually has, because other countries are able to create bypass routes,” Rauball, at Kpler, said.