The US has been active in the Middle East for decades, and its involvement has varied from the invasion of Iraq, through the fight against the Islamic State, to sending weapons to Israel and Saudi Arabia.
Experts point to sources of energy, trade routes, geopolitical stability, counter-terrorism and the permanent US alliance with Israel as factors driving Washington's involvement in the region.
US troop levels in the Middle East have fallen dramatically since their peak in 2007, when there were about 160.000 in Iraq alone.
Now there are fewer than 40.000 of them in an area that stretches from Egypt to Afghanistan and is under the control of the US military's Central Command.
Whether to further reduce the American presence becomes a key strategic question for Washington.
Here's an overview of some of the issues.
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Energetics
The vast reserves of oil and natural gas in the Middle East, in countries such as Saudi Arabia, Iran, Iraq, Kuwait and the United Arab Emirates, have been a major factor in shaping American policy for decades.
But a surge in U.S. oil and gas production at home over the past 15 years, fueled largely by the rise of shale gas, has made the country much less dependent on energy imports.
It is now an exporter of both oil and natural gas.
The global oil market, however, remains tightly coupled, and disruptions to supplies from the Middle East could significantly affect oil prices and thus economic stability.
Also, China, unlike the USA, is highly dependent on oil from the Middle East, points out Gilbert Ashkar, professor of international relations from the School of Oriental and African Studies (SOAS) in London.
This means that "controlling the Middle East gives the US enormous leverage over China," he says.
Economic interests and ship traffic
The Middle East is a key market for American goods and services, especially military equipment.
It was the global region that received the most US arms exports between 2019 and 2023, according to the Stockholm Institute for International Peace Research.
The institute says that 38 percent of US arms exports went to the Middle East, with the main recipients being Saudi Arabia, Qatar, Kuwait and Israel.
In addition, the Middle East is vital to global maritime trade, says Hugh Lovett, regional specialist at the European Council on Foreign Relations (EFCR).
The war in Gaza has triggered attacks by Yemen's Iran-backed Houthi rebels on shipping in the Red Sea.
More than 17.000 ships pass through the Red Sea each year - accounting for an estimated 12 percent of global trade - carrying food, medicine, fuel and other basic necessities to all parts of the world.
The US intervened.
Along with Great Britain and supported by several other international allies, they attacked Houthi positions in January and February 2024, in response to the group's attacks on shipping in the Red Sea.
This shows that "they continue to prioritize freedom of navigation on global waterways," says Lovett.
He says that Egypt's Suez Canal and the narrow Strait of Hormuz near Iran are also of key importance.
"These are world shipping routes that are still important for the American economy," he adds.
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Geopolitical stability
The Middle East's strategic location linking Europe, Asia and Africa is vital to US trade and military operations, with US bases located in Bahrain, Qatar and Kuwait.
The US still has a large presence to prevent a single power from becoming dominant and threatening stability, said Merissa Kurma, director of the Middle East Program at the Wilson Center, a Washington think tank.
Historically, American interests in the region have been motivated by oil and a desire to contain the threat of communism, she says, but now, beyond that, they also want to maintain influence and superpower status.
The region "remains a key arena for competition with major powers such as China and Russia," she adds.
Kurma also says that the war in Gaza is a reminder of how unstable the region is, "especially when the United States of America is restrained and politically withdrawn in relation to the resolution of permanent conflicts - especially the Palestinian-Israeli conflict as well as Iranian military expansionism in the region."
counterterrorism
The US military presence in recent decades "was partly a reaction to growing terrorist threats from the region," says Khaled Elgindu of the Middle East Institute (MEI).
But it was also "the main impetus for violent extremism," he adds, noting that the extremist Islamist group Al Qaeda cited the presence of American troops in Saudi Arabia as one of the main reasons why it carried out the September 11 attacks in America in 2001.
Although much of the US initiative to destroy Al Qaeda was focused on Afghanistan and Pakistan, it also included activity and alliances in the Middle East as well.
And more recently, a global coalition led by the US has supported local forces in expelling the Islamic State from the areas it controlled in Syria and Iraq.
The head of the group, Abu Bakr Al Bagradi, committed suicide in 2019 during the incursion of American special forces into northwestern Syria.
The region is also home to several other groups designated as terrorists by the US and other countries, including Hamas and Hezbollah.
Elgindi says the US presence in the region has been a "huge recruiting aid" for groups such as the Islamic State and its affiliates.
"Terrorism exists because of bad governance, lack of self-determination, and perceived tyranny and imperialism in the Middle East," says Natasha Hall, an expert at the Center for Strategic and International Studies think tank in Washington.
"And that's why, when the United States of America tries to suppress the symptoms of terrorism, it doesn't solve its drivers. It just predictably survives and grows," she adds.
Israel
"The security of Israel has been one of the highest priorities of the US for the better part of the last 60 years," says Elgindi.
This is partly motivated by ideological affinity between the allies, as well as strong domestic political pressure on American leaders to support Israel.
SOAS' Ashkar says Washington's continued support for Israel is also an "extremely effective" investment, making it a key military ally in the region.
The US, however, brokered important peace agreements between Israel and its Arab neighbors, including Egypt - and more recently the United Arab Emirates and Bahrain.
Elgindi says the ongoing war between Israel and Hamas has drawn the U.S. into more direct forms of involvement, such as when it sent warships to the eastern Mediterranean after Hamas's Oct. 7 attacks, and when it helped mitigate an Iranian missile attack on Israel in April.
He adds that Biden's personal and ideological commitment to Israel "probably exceeds that of any other American president in history," which, he says, explains the "contradictions in his policies."
"Despite serious and growing differences between the US and Israel over the actions and goals of the ongoing war in Gaza, the Biden administration has provided almost unlimited military, political and diplomatic assistance to Israel's military campaign at virtually every turn," he says.
Hall says the current level of American support is unlikely to change if former President Donald Trump returns to the White House.
But she believes that US support for Israel now "will have a huge geopolitical cost in the years and decades ahead" as the US is "challenged for its perceived hypocrisy".
What next?
Views differ on how much the US should continue to prioritize the Middle East.
Elgindi says he doesn't see the US withdrawing from the region "in the foreseeable future."
In order to do that, "a certain kind of paradigm shift is needed," which includes a rethinking of the relationship between the US and Israel, he adds.
And Ashkar says that "an American exit would create a vacuum that could be filled by China and Russia."
But, he says, given the limited appetite of American citizens for boots on the ground in the Middle East, one of the priorities for the U.S. now will be developing its ability to conduct long-range warfare, such as with drones and missiles, in the region.
Others, however, such as Keli A. Griko of the Stimson Center think tank in Washington, argue that the US should withdraw its forces from the Middle East.
This would allow them to shift resources "to where they are most needed, especially in the Indo-Pacific," she says.
She claims that American interventions have only further fueled anti-American sentiment in the Middle East, adding that America's support for Israel in recent months has "delivered another big blow" to the US image in the region.
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