The US Air Force has once again delayed development of its long-range standoff (LRSO) weapon, announcing it will push back a contract award by three years until fiscal year 2018.

The service, which had expected to award a contract in fiscal year 2015, attributes the delay to budget constraints in a document posted on the government’s procurement website.

The latest delay follows a two-year delay — from 2013 to 2015 — announced by the USAF in early 2013.

The USAF’s five-year spending plan, released on 11 March, provides move details about the service’s plan for LRSO development.

According to those documents, the USAF proposes to spend $4.9 million on LRSO in fiscal year 2015. That’s $35.6 million less than the $40.5 million that the USAF had previously expected to spend on the project that year.

The change makes way “for higher Air Force priorities,” says the service.

LRSO funding under the plan would then double each year for the next three years before jumping to nearly $145 million in fiscal year 2019.

The LRSO programme seeks to develop a weapon that can penetrate and survive integrated air defence systems, according to Pentagon budget documents.

LRSO weapons would be carried by the service’s future long-range strike bomber (LRS-B), which the service hopes to field by the mid-2020s.

The USAF is required to have an operational LRSO weapon by around 2030 under the National Defense Authorisation Act for fiscal year 2014, signed by president Obama late last year.

Though that document doesn’t provide a firm date, it does require the weapon reach initial operational capability (IOC) before the service retires its nuclear and conventionally armed Boeing AGM-86B air-launched cruise missiles.

The USAF has said it plans to extend the service life of those weapons, which are typically launched from Boeing B-52 aircraft, until at least 2030.