The new Air Force One, which President Trump flew on earlier this week to Turkey, lacks the same defensive countermeasures that were security features of the old model, including its advanced antimissile capabilities, according to multiple officials who have been briefed on how the jet was retrofitted.

Experts say the absence of those capabilities on the Boeing 747-8 aircraft, which was donated by Qatar, creates potential risk in using the jet abroad, a dynamic underscored by the abrupt decision on Wednesday for Mr. Trump to leave Turkey on the old Air Force One at the urging of the Secret Service.

The episode is intensifying the focus on Mr. Trump’s demands to rapidly retrofit the donated 747 to replace an aging fleet that had served as the official presidential planes.

Lawmakers have called on the administration to disclose whether the overhaul of the Qatari plane, which the Air Force oversaw in the course of the last year, provided sufficient security upgrades. The safety of the aircraft is critical not only for the president, but also for the large entourage of White House staff, Secret Service officials, journalists and guests who fly aboard.

Mr. Trump pushed for the new plane to be put into use as quickly as possible and frequently complained that the old presidential aircraft was not impressive enough to take on international trips.

On Thursday, the White House did not address specific questions about the new plane’s capabilities, but defended its safety.

“The new Air Force One is a state-of-the-art aircraft that has been fitted with high-level security protocols that ensure the safety of the president and his staff,” Steven Cheung, the communications director, said in a statement. “As the president has said recently, there are many enemies of America who have their sights on him, and we use every tool at our disposal to address those threats.”

The Air Force has declined to discuss specifics around security systems on the retrofitted Qatari plane, which is being used as a “bridge” aircraft while two Boeing jets that will be part of the permanent presidential fleet are being finished.

But in a statement it made when it announced that the donated jet was ready to transport the president, it acknowledged that the temporary plane did not have all the equipment usually found on an Air Force One.

“No risk was taken in security, safety or mission communications,” the Air Force said in a statement on June 19. “But the collective team made trades on some of the less commonly used mission sets that Boeing must deliver to support the next 40 years.”

The Air Force would not say what it meant by “less commonly used mission sets.”

However, officials who have been briefed on the retrofitting of the Qatari jet, who spoke on the condition of anonymity to describe its security features, said it did not have the same counter-defensive capabilities of the previous model.

Two former Air Force officials, who had both been involved in the effort to replace the older Air Force One planes, said they were surprised to see Mr. Trump fly on the new jet overseas, where there are greater security risks. Turkey, where Mr. Trump attended a NATO summit, borders Iran, which the United States pummeled with renewed strikes this week.

The former officials were not involved with the retrofitting of the Qatari jet, but said the speed of the project meant there would not have been enough time to make all of the security modifications that are traditionally associated with a fully equipped presidential aircraft.

“Time didn’t permit all the normal Air Force One modifications, so some mix of security, communications and support is missing,” said Frank Kendall, the former Air Force secretary who was in charge of the department as it tried to push Boeing to accelerate its long-delayed contract to deliver two new Air Force One planes.

“With the Iran situation, this could be of concern,” Mr. Kendall said. “Frankly, I’m surprised to see this plane used outside the U.S.”

Andrew P. Hunter, the former Air Force assistant secretary who was in charge of the Air Force One program during the Biden administration, also said that a true retrofit of a 747 jet to prepare it to become Air Force One would require more than a year of work.

The day before Mr. Trump left for Turkey, Senate Democrats wrote to the Air Force asking questions about the modifications to the Qatari plane and questioning whether it had all the necessary security upgrades.

“Trump’s own statements — including his celebration of ‘a level of luxury that nobody’s ever seen before’ — make it clear that these decisions prioritized Trump’s personal comfort and tastes over U.S. national security,” they wrote in the letter sent by Senator Christopher S. Murphy, Democrat of Connecticut, and 12 other senators.

The older planes that served as Air Force One included a defensive system designed to defeat heat-seeking missiles. That capacity is also planned to be included in the new Boeing planes, according to three former Pentagon officials.

Different parts of the defensive systems are visible on the old Air Force One, under the wing of the plane and on its tail. They are not observable in photographs of the new Qatari plane, according to a third former Air Force official, who spoke on the condition of anonymity to describe the security protocols.

Missile defense systems on Air Force One have seen little use in the history of the aircraft, but have nevertheless been considered critical aspects of the plane’s security features.

The Pentagon published specifications for the Boeing aircraft now under construction that indicate the new jets will include a “self-defense system” and “mission communication system,” as these and other upgrades are needed “to enable the president to execute the duties of head of state, chief executive, and commander in chief.”

U.S. officials have said that Iran has been targeting Mr. Trump since he ordered the drone strike that killed Qassim Suleimani, in January 2020. During the 2024 campaign, the Secret Service increased protection for Mr. Trump, even before the attempt on his life in Butler, Pa., because of intelligence about Iran’s plotting against him.

Despite the resumption of intense U.S. strikes on Iran, American policymakers briefed on the current intelligence do not believe that Iran has a current plan to kill Mr. Trump during this period. A U.S. official, who spoke on the condition of anonymity to describe intelligence assessments, said that Iran had a clear understanding of what kind of deep provocation any attempt on Mr. Trump’s life would be and the intensity of an American response.

Nevertheless, the Secret Service was concerned enough about Mr. Trump’s proximity to the country while in Ankara to force the president to swap planes on the way out of the country, as The New York Times first reported Wednesday.

In announcing the change, Mr. Trump offered a different story: He claimed that he was flying out on the old plane so the new jet could leave early and make stops at U.S. military bases to show it off to the troops because the aircraft is “magnificent.”

One former senior White House official involved in discussions about military aircraft used for presidential travel said that there were frequently points of tension between White House staff and the military advisers and Secret Service over travel plans when security questions emerged.

But when the military experts demanded changes, White House officials generally let them prevail, with “course of action” plans that mitigated potential threats.