The open-ended crisis in the Middle East has begun to squeeze the Pentagon, fueling unease over the U.S. military’s ability to balance imminent threats to American interests there with longer-term objectives as Russia and China test Washington elsewhere in the world.

Signs of strain were underscored in recent days by a decision to withdraw the sole U.S. aircraft carrier in the region, the USS Abraham Lincoln, whose imposing presence defense officials credit with helping to contain the ongoing violence between Israel, Iran and its network of well-armed proxies.

The Biden administration has kept at least one, and sometimes two, aircraft carriers in the Middle East for more than year, since the Hamas-led attack on Israel in October 2023 spawned a multifaceted conflict with no end in sight. When the Lincoln departs in coming days, the Defense Department instead will rely on a mix of other forces, including naval destroyers, B-52 bombers and land-based fighter jets, to sustain its expansive and potentially combustible deterrence mission that stretches from the eastern

Mediterranean to the Persian Gulf and other volatile shipping routes around the Arabian Peninsula.

Maj. Gen. Patrick Ryder, a Pentagon spokesman, told reporters that the new deployments will provide a “significant amount of capability on par with what we’ve been doing in the Middle East” since the crisis there began.

The shake-up occurs as the Pentagon grapples, too, with shortages of key munitions it has used to fend off attacks by Yemen’s Houthis, who have waged an aggressive, months-long campaign targeting commercial vessels in the Red Sea and Gulf of Aden, and to help Ukraine resist Russia’s nearly three-year-old incursion. U.S. military officials have acknowledged also that they are struggling to distribute enough air-defense systems to protect assets and allies in Eastern Europe along with those in the Middle East, and analysts warn the strain could hinder Washington’s ability to defend Taiwan in the event of a Chinese invasion.

The Lincoln, and the dozens of combat aircraft that operate from its flight deck, was scheduled to deploy to the Asia-Pacific region as part of a Pentagon strategy meant to show force in an area where key U.S. partners have had to contend with an expansionist China and a wildly unpredictable North Korea. In August, after tensions between Israel and Iran hit a peak with the killing of Hamas leader Ismail Haniyeh in Tehran, the carrier was ordered from the Pacific to the Middle East and later had its deployment extended as senior officials evaluated the potential risks of making such a significant shift.

The quandary simmered for weeks, with Defense Secretary Lloyd Austin and Gen. Charles Q. Brown Jr., chairman of the Joint Chiefs of Staff, weighing various options mindful of the mounting demands the Middle East conflict has imposed on U.S. personnel and equipment, and Washington’s ability to address other pressing geostrategic objectives. Brown said in a recent interview that the Pentagon must “step back and take a look” at the totality of what’s being asked of the military, “not just in the Middle East but really all around the world.”

The chairman’s force-posture recommendations go to Austin, who ultimately makes the weighty decisions that could create long-term complications for the Pentagon. Those considerations require “very real trade-offs,” said a senior defense official familiar with this thinking, who like some others spoke on the condition of anonymity to discuss sensitive military movements.

“I don’t think there are any easy decisions,” the official said.

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Outsize demands on the Navy

When the Gaza war began, the Pentagon moved quickly to reinforce its presence in the Middle East, shuffling around tens of thousands of troops, realigning defenses and deploying dozens of attack aircraft to complement Israel’s Iron Dome air defenses and project a message of deterrence to Iran and its proxies. The ongoing crisis has affected the Navy like no other service.

In the days after Hamas attacked Israel, President Joe Biden announced that a deployment of the aircraft carrier USS Gerard Ford and its escort ships would be extended to help protect the Jewish state as another carrier, the USS Dwight D. Eisenhower, was dispatched to the region. The Eisenhower strike group also carried out an extended assignment, from November 2023 until June. In that time, U.S. personnel launched hundreds of weapons at a total cost of more than $1 billion, according to Navy data.

The Eisenhower was replaced in the Middle East by the carrier USS Theodore Roosevelt, and Austin ordered the Lincoln to join it after the assassination of Haniyeh prompted Iranian threats of retaliation. In late September, when Israel’s killing of Hezbollah leader Hasan Nasrallah in Lebanon triggered additional declarations from Tehran, Austin extended the Lincoln. In recent days, it was

in the Gulf of Oman with several escort ships, defense officials said.

Another aircraft carrier, the USS Harry S. Truman, deployed from Virginia in September and in recent days was in the North Sea for a scheduled deployment to Europe, where Russia’s actions in Ukraine and beyond have been met with alarm. Officials said the Truman could be diverted to the Middle East if necessary.

Another concern, officials say, is the Wasp Amphibious Ready Group, a three-ship flotilla carrying U.S. Marines and sailors and various aircraft that has been in the eastern Mediterranean since late June due to concerns that a U.S. evacuation from Lebanon may be necessary. Those ships and personnel have been deployed since April, and several defense officials familiar with the situation said there is no similar replacement ready to step in because of the Navy’s long-standing struggle to maintain its modest fleet of such vessels.

James Foggo III, a retired Navy admiral, said the extended deployments have enhanced security in the Middle East but will result in second-order effects that include delayed maintenance, upended training schedules and shortfalls in munitions.

“Two more months - 60 more days - of wear and tear on the ship means more things need to be fixed,” Foggo said. “It’s very important to be able to fix the ship … and to get it back in the rotation.”

The Navy’s top officer, Adm. Lisa Franchetti said in a recent event at the Atlantic Council that she is focused on addressing challenges that have caused delays when ships require extensive maintenance after deployments. Franchetti said she has set a “stretch goal” of having 80 percent of the Navy’s ships and aircraft available to be surged in a crisis by 2027. That number, she told reporters recently, was 36 percent in 2022 and had come up to 67 percent as of June.

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A drain on weapons stocks

In the past year, the United States has spent at least $22.7 billion on military aid to Israel and U.S. operations in the region, according to a cost analysis by the Brown University’s Watson Institute for International and Public Affairs. The authors of the analysis said that is a “conservative” estimate that does not include additional U.S. security assistance provided to Egypt and Saudi Arabia and other U.S. partners.

More than $4.8 billion has been spent to boost offensive and defensive operations in the Red Sea and Gulf of Aden where, the analysis found, “the U.S. Navy has been intercepting Houthi drones and missiles on a near-daily basis.” The Watson Institute’s report calls the operation “the most sustained military campaign by American forces” since the height of the Pentagon’s extended bombing campaign against the Islamic State in Iraq and Syria.

William D. Hartung, one of the co-authors, said in an interview that one of the major problems is “the context in which this is happening.” He cited the Ukraine war, the conflict in the Middle East and the need to keep munitions on hand for any confrontation with China.

Rising tensions with China have focused heavily on its plans for the self-governing island of Taiwan, which China claims as part of its territory. China has dramatically expanded the size of its military and its presence in the South China Sea in recent years, and

Chinese leader Xi Jinping has suggested Beijing may eventually attempt to seize it by force. The United States has sought to counter China’s influence by expanding its networks of allies and partners in the region.

Hartung, an analyst at the Quincy Institute for Responsible Statecraft, which advocates military restraint, said that after years of operations in Iraq, Afghanistan and other countries, the United States has shifted from having American boots on the ground to a strategy focused on arming allies and partners.

“It ends up that could have its own disastrous results,” Hartung said, alluding in part to the depletion of U.S. stocks. “It’s not as safe an alternative as maybe they thought.”

Foggo, the retired Navy admiral, said it is clear the Biden administration has sought to grow production of key munitions. But Washington could still do more, he said, including utilizing the Defense Production Act, a law that grants the president power to take control of key components of industry to bolster national defense.

During a recent panel discussion, Becca Wasser, a senior fellow in the defense program at the Center for a New American Security, said it appears the Houthis are waging a “cost-imposition campaign” intended to wear down the United States until it is forced to change its policy or retreat. She cited the Navy’s heavy use of pricey Tomahawk cruise missiles and the Standard Missile-2, a surface-to-air missile that sailors have used to ward off incoming drones and missiles in the Red Sea.

Should the Navy end up in any conflict with China, Wasser noted, it’s probable the United States would need to rely on such rounds - and a lot of them.

“The rate of fire for those is really high,” said Wasser. “If you look at the rate of build, that circle does not square.”