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 US military has recently moved other assets into the Persian Gulf amid concerns about a confrontation with Iran, the AP news agency reports.

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.