The F-22 Raptor is the nation’s most modern, fifth-generation fighter bomber. (AP)

The United States has deployed a number of stealth jets, its most modern, fifth-generation fighter bomber, to an air base in Southwest Asia, according to the Air Force.

The service would not say where the F-22 Raptors would be based, but the U.S. military has recently moved other assets into the Persian Gulf amid concerns about a confrontation with Iran.

An Air Force spokesman, Capt. Phil Ventura, described the deployment as “regularly scheduled” activity being undertaken to strengthen military-to-military relationships, regional security and work on “tactical interoperability.”

He said the number of F-22s involved and the length of their deployment were not being released to protect operational security.

The transfer of warplanes to the gulf comes as the United States and five other world powers are preparing for critical talks with Iran on proposed curbs to its nuclear program. At a meeting two weeks ago, Iran agreed to discuss its nuclear future without preconditions, and senior Iranian officials have since hinted at a willingness to scale back portions of the country’s program in exchange for relief from economic sanctions.

Despite the more conciliatory tone, the Obama administration has sought to keep up the pressure on Tehran, warning that the economic pain will worsen unless Iranian leaders agree to broad changes to ensure that Iran’s nuclear facilities cannot be used to make nuclear weapons. Iran has consistently claimed that its nuclear program is peaceful. The next round of negotiations have been scheduled for May 23 in Baghdad.

Last month, amid Iranian threats to close the Strait of Hormuz, Adm. Jonathan Greenert, chief of naval operations, told reporters that the U.S. military would be doubling to eight the number of its minesweepers in the region. He also said four more CH-53 Sea Stallion helicopters with mine-detection capability would be sent to the region.

Also last month, new F-15 fighter jets with the 104th Fighter Wing of the Massachusetts Air National Guard were sent on their first overseas deployment to an undisclosed Central Command location. At a ceremony marking their departure, Col. Robert Brooks, the unit commander, said that “should Iran test the 104th,” the unit would be ready, according to the Daily Hampshire Gazette.

Aviation Week, which first reported the deployment of the Raptors, quoted industry sources as saying the planes would operate out of Al Dhafra Air Base near Abu Dhabi, the capital of the United Arab Emirates.

The Al Dhafra base is already being used by KC-10 refueling aircraft, along with U.S. surveillance aircraft such as the piloted U-2 and the unmanned Global Hawk.

Staff writer Joby Warrick contributed to this report.