The aircraft carrier U.S.S. Abraham Lincoln’s supply problems began soon after the first day of the war, as Iranian missiles and attack drones fell on a Navy base in Bahrain.

The Iranian attack, retaliation for the U.S.-Israeli assault on Tehran, destroyed much of the base. And as it went up in smoke, so did a major logistics hub that the Navy has relied on for decades.

The Navy needed a Plan B to continue feeding the sailors working around the clock to keep warplanes flying strike missions, and later to maintain a blockade of Iran’s ports.

With the threat of Iranian attacks at other ports in the region, the Pentagon looked to a base under British command on the island of Diego Garcia as its supply hub, which is south of the Maldives and roughly 2,200 miles from where two aircraft carrier strike groups have been operating in the Gulf of Oman.

The loss of the hub in Bahrain has contributed to a host of reported problems on carriers supporting operations against Iran, as Democratic senators raise concerns about the Lincoln’s 5,000 sailors and their nearly nine-month deployment.

Senator Richard Blumenthal, Democrat of Connecticut, said in a letter to Defense Secretary Pete Hegseth that the reported problems included shortages of basic supplies and the deteriorating mental health of its crew members.

On Friday at a military air base in Maryland, Mr. Trump dismissed those concerns. “That ship is moving right now, or very shortly, and it’s being replaced with another, very similar, ship,” he said.

The Lincoln’s replacement is the Japan-based carrier U.S.S. George Washington, which earlier this week was heading west through the Strait of Malacca in Indonesian waters en route to the Middle East.

Another carrier, the U.S.S. George H.W. Bush, has been operating in the Middle East for months since deploying from Norfolk on March 31.

When asked if the carrier deployments were too long, the president said, “No, no, no, not nearly long enough.”

Mr. Hegseth had a similar response on Thursday when a reporter asked how long the United States could maintain its blockade of the Strait of Hormuz.

“We can hold it as long as we need to, indefinitely,” he replied.

At the war’s outset, Keir Starmer, then the British prime minister, denied the Pentagon access to Diego Garcia for use in the operation against Iran. That decision drew Mr. Trump’s ire, and Mr. Starmer ultimately relented on March 1, granting the U.S. military access to the island for what he described as a “specific and limited defensive purpose.”

A U.S. military official, who spoke on the condition of anonymity to discuss sensitive logistics, said the Navy began using Diego Garcia as the main shipment point shortly after the Navy’s base in Bahrain was heavily damaged.

The use of Diego Garcia as the Navy’s new logistics hub may explain why Iran fired two medium-range ballistic missiles at the island on March 20.

One of the missiles fell into the Indian Ocean short of its target. A Navy warship shot down the other.

The San Diego-based Lincoln has been at sea for nearly nine months without what the Navy calls a “liberty port” — where sailors can get off the ship for a few days.

Bahrain is one of the two ports where U.S. aircraft carriers in the region have typically moored so their crews can get some downtime. The other, the Emirati port of Fujairah on the Gulf of Oman, is also well within the range of Iranian missiles.

The Trump administration relied on yet another carrier, the U.S.S. Gerald R. Ford, in the Caribbean for its pressure campaign against Venezuela and later extended its deployment to the Middle East to launch airstrikes against Iran. So far the war has seen the commitment of a significant portion of the Navy’s fleet of aircraft carriers, which will go down to 10 with the expected retirement of U.S.S. Nimitz next year.

While six months is the typical length of a Navy deployment at sea in peacetime, some carriers have done far longer stretches at following the Sept. 11 attacks. The Ford’s 326-day deployment, however, broke the record for the longest by a carrier since the Vietnam War.

But in that war, carriers assigned to Yankee Station, a section of the Pacific off the coast of Vietnam, would often head to the Navy base at Subic Bay, Philippines — a short two-day transit away — where sailors could take a break from running nonstop flight operations and the ship could load up on ordnance, food, fuel and other necessary supplies.

By tradition and Navy regulation, the commanding officer of a warship can request a “beer day” for their crews when they have been at sea for 45 straight days or longer. Given the Lincoln’s time at sea, the crew would have been eligible for five beer days already.

A spokesman for the U.S. Fifth Fleet, which covers naval operations in region and would authorize beer days, did not immediately respond to a request for comment on Friday about whether any of the ships participating in the Iran war had requested them.

In an interview, Representative Mike Levin, Democrat of California, said that his constituents included sailors aboard the Lincoln, and that their family members had reached out to express their concerns about the deployment.

“It gets back to that big picture, which is: What is the mission here?” Mr. Levin said. “That’s what the families want to know.”