WASHINGTON — The Air Force moved ahead with two critical nuclear modernization programs on Friday, releasing requests for proposals for its intercontinental ballistic missile replacement and a nuclear cruise missile.

The Ground Based Strategic Deterrent (GBSD), which replaces the 1960s-era Minutemen III ICBM, and the Long Range Standoff (LRSO) weapon, which will supersede the AGM-86B Air Launched Cruise Missile, are seen by the service as pivotal for maintaining the nuclear triad and an effective strategic deterrent.

However, both programs have come under fire by lawmakers and analysts who assert that the the weapons are too costly, duplicative or even that they could add to global instability.

For the GBSD program, the Air Force plans to award up to two 36-month technology maturation and risk reduction contracts by the end of fiscal year 2017. After downselecting to a single bidder, it would then deploy the ballistic missile system in the late 2020s.

The service envisions GBSD as an integrated system that includes launch and command and control capability. It also wants the system to be flexible and adaptable to future threats, as well as effective in an anti-access, area-denied (A2/AD) environment — a task the aging Minuteman III ICBMs have trouble standing up to.

"This request for proposals is the next step to ensuring the nation's ICBM leg of the nuclear triad remains safe, secure and effective" Maj. Gen. Scott Jansson, Air Force program executive officer for strategic systems, said in a statement.

The fact that the service is pursuing a cost-plus contracting arrangement could invite congressional meddling. Senate Armed Services Committee Chairman John McCain has attacked the Air Force for its use of cost-plus contracts for the B-21 bomber, and is pressing for greater use of fixed-price deals where industry takes on greater risk.

GBSD proposals are due in October.

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For the cruise missile competition, the Air Force plans on awarding up to two contract awards for LRSO technology maturation and risk reduction by the fourth quarter of fiscal 2017. By the end of this 54-month stage, contractors will have developed a preliminary design "with demonstrated reliability and manufacturability," the service said in a news release.

After a competition, the Air Force will downselect a single vendor, with fielding scheduled to kick off by 2030.

Air Force leaders have argued that it needs a nuclear-armed cruise missile for its bomber fleet to have standoff capability against enemies with more sophisticated air defenses. The legacy ALCM, which was fielded in the 1980s, is still performing well considering its 10-year design life, but is becoming less effective as threats advance.

Speaking to a congressional panel in February, Gen. Robin Rand, commander of Air Force Global Strike Command, said LRSO "will ensure the bomber force can continue to hold high-value targets at risk in an evolving threat environment, to include targets within an area-denial environment."