Northrop Grumman has withdrawn from participating in the US Navy’s competition to develop the MQ-25 Stingray, saying the company would have been unable to execute the programme under the terms of the service’s request for proposals.

The announcement came as a surprise during a 25 October third quarter earnings call with Northrop CEO Wes Bush, who told analysts the company would not submit a bid for the Stingray following aggressive internal analysis.

Northrop’s decision leaves three other companies bidding for the contracts to compete for the MQ-25 contract: Boeing, General Atomics-Aeronautical Systems Inc and Lockheed Martin. It also comes after the USN has narrowed the scope of the MQ-25 mission to providing in-flight refueling for manned, carrier-based fighters. The refueling mission evolved after the USN discarded a series of previous concepts for a carrier-based, unmanned jet, which included stealthy and non-stealthy versions of surveillance and attack requirements.

“Our objective is not just to win, but if you can’t execute on it then you’ve done the wrong thing,” Bush says. “We’ve worked hard to have great clarity on what our objectives are. When you’re entrusted by the US government to do something in the defence arena, that’s a bond of trust.”

The announcement marks the third time in the last decade Northrop has pulled out of a bid for a contract to develop a US military aircraft. Last February, the company announced it would bow out of the US Air Force’s T-X trainer programme after Bush hinted during an earnings call that Northrop was reassessing the business case for submitting a bid. In that case, Northrop decided the financial benefits of winning the contract outweighed the costs.

In 2010, Northrop withdrew a bid for the USAF’s air refueling tanker programme based on the Airbus A330 multi-role tanker-transport, forcing Airbus to compete as a prime contractor against the ultimately victorious Boeing KC-46.

The US Navy has changed requirements for the Stingray programme several times. The concept has evolved from a stealthy, strike and intelligence, surveillance and reconnaissance platform dubbed the Unmanned Carrier Launch Airborne Surveillance and Strike (UCLASS), into a more pared down Carrier Based Aerial Refueling System, which the navy designated MQ-25.

In September, a Government Accountability Office report emphasized a no-frills version of the MQ-25, focusing on the basic ability to operate from a carrier and adjusted the mission focus for air refueling. Last year, the Pentagon attempted to rein in the Stingray’s projected development costs by directing the navy to shift its focus away from surveillance and toward air refueling.