Fighting across several oil-producing regions is putting growing pressure on energy markets, raising the risk that supplies could be constrained by multiple maritime chokepoints and product shortages at the same time.

The concern is not just the volume of crude at risk, but the concentration of trade routes. The Strait of Hormuz is the main sea passage out of the Persian Gulf, while Bab el-Mandeb connects the Red Sea with the Gulf of Aden and the wider Indian Ocean. Disruptions in either route can force longer voyages, raise shipping costs and complicate delivery schedules for both crude oil and fuels.

Over the weekend, the U.S. and Iran paused attacks on each other in the Persian Gulf while diplomatic efforts continued. Iran and Oman are also holding separate talks aimed at reopening the Strait of Hormuz.

However, the U.S. and Iran’s neighbors are unlikely to accept any agreement that acknowledges Tehran’s control over the narrow waterway. At the same time, Iran-backed Houthi rebels are threatening vessels in the Bab el-Mandeb Strait, a route Saudi Arabia has used to export oil while bypassing the Strait of Hormuz.

Ships can avoid the Bab el-Mandeb Strait by using the Suez Canal to enter or leave the Red Sea, but the canal cannot accommodate the largest oil tankers. When those vessels cannot use the canal, the main alternative is a longer route around Africa’s Cape of Good Hope, which ties up ships for longer and can reduce available tanker capacity.

There is also concern that Iran could attempt to target the Suez Canal.

“So we are starting to talk about the kind of no way out scenarios because of this new Red Sea unrest,” Helima Croft, head of global commodity strategy at RBC Capital Markets, told CNBC on Thursday.

In another theater, Ukraine has been striking Russian oil infrastructure across the country, as well as tankers carrying Russian oil and refined products in the Black Sea.

Russia is among the world’s largest diesel producers, but damage to its refineries has reduced supplies, prompting Moscow to ban exports in order to conserve barrels for domestic consumers. Diesel is closely watched because it is used across trucking, farming, construction and industrial activity, making regional shortages more difficult to absorb than a headline crude-oil disruption alone.

“So it’s really tightening the products market as well as the crude market,” Croft said. “And again, this administration now in Washington—they’re facing an everything everywhere all at one situation.”

The pressure extends beyond the Persian Gulf, Red Sea and Black Sea. A recent Ukrainian attack also targeted an Iranian ship in the Caspian Sea that was suspected of ferrying military supplies between Iran and Russia.

Susan Bell, senior vice president of downstream research at Rystad Energy, warned that the strain on refined fuels is more severe than the disruption facing crude oil supplies.

In an interview with Bloomberg TV on Wednesday, Bell said that when the Iran war began, commercial and strategic crude oil stockpiles totaled 4.4 billion barrels. By comparison, inventories of refined products such as gasoline, diesel and jet fuel stood at only about 1.4 billion barrels.

Both crude and refined product inventories have since fallen by 200 million barrels each, leaving a much smaller buffer for refined fuels. That has driven a sharp widening in so-called crack spreads, the difference between oil prices and fuel prices.

Bell said the gasoline crack spread in the U.S. was about $8 a barrel at the start of the war, but has since risen to $40-$50. Wider crack spreads are a sign that fuel prices are rising faster than crude, reflecting tighter product supply and stronger pressure on refiners and consumers of gasoline, diesel and jet fuel.

“Products just had a lot less to start, with so the crisis is intensifying on product stocks,” she said.

Meanwhile, President Donald Trump has few remaining policy levers available during the second phase of the Iran war as oil prices again approach $100 per barrel.

The U.S. and other countries have already depleted much of their emergency reserves. A gas tax holiday is unlikely because it would need approval from a divided Congress. U.S. oil producers and refiners are already operating near all-time highs, and the administration has already waived the Jones Act, allowing more ships to move fuel from the U.S. Gulf Coast to the more supply-constrained West and East coasts.

That leaves officials watching not only crude benchmarks, but also shipping routes, refinery outages, product inventories and the availability of tankers able to move fuel between regions.

If both the Bab el-Mandeb Strait and the Strait of Hormuz are nearly closed, oil prices could easily rise in August back toward the late-April high of $124 per barrel, Dan Pickering, founder of the Pickering Energy Partners consulting and research firm, told Fortune’s Jordan Blum.

“If we wind up with a de-facto closure of the strait and this Houthi threat shuts down the Red Sea, then I think it gets bad pretty fast during August,” Pickering said. “We don’t have multiple months because we’re already starting from a tougher spot. It’s going to be on us pretty quickly.”