DUBAI, United Arab Emirates (AP) — Thousands of Marines backed by advanced US fighter jets and warships are slowly building up a presence in the Persian Gulf. It’s a sign that while America’s wars in the region may be finished, its conflict with Iran over its advancing nuclear program continues to worsen, with no solutions in sight.

The dispatch of the troop-and-aircraft-carrying USS Bataan to the Gulf, alongside stealth F-35 fighters and other warplanes, comes as America wants to focus on China and Russia.

But Washington is seeing once again that while it’s easy to get into the Middle East militarily, it’s difficult to ever get fully out — particularly as Iran now enriches uranium closer than ever to weapons-grade levels after the collapse of its 2015 nuclear deal with world powers.

There is no sign that diplomacy will revive the deal soon, and Iran in recent weeks has resumed harassing and seizing ships trying to pass through the Strait of Hormuz. Some 20% of the world’s oil passes through the narrow waterway connecting the Persian Gulf to the wider world.

For hardliners in Tehran’s theocracy, the move projects power to surrounding nations as part of a wave of assaults attributed to Iran since 2019. It also serves as a warning to the US and its allies that the Islamic Republic has the means to retaliate, particularly as American sanctions result in the seizure of ships carrying Iranian crude oil. Worries over another seizure likely has left a ship allegedly carrying Iranian oil stranded off Texas as no company has yet to unload it.

For the US, keeping the Strait of Hormuz open to shipping remains a priority to ensure global energy prices don’t spike, particularly as Russia’s war on Ukraine pressures markets. Gulf Arab nations need the waterway to get their oil to market and worry about Iran’s intentions in the wider region.