The U.S. Navy’s plan to release its unmanned aerial vehicle (UAV) carrier fleet in 2020 has been delayed. In addition, it is withholding the release of its request for proposal (RFP) for the UAVs themselves.

According to the U.S. Naval Institute News (USNI), the Navy has announced that it will push back its fielding date of its Unmanned Carrier Launched Surveillance and Strike (UCLASS) program to at least 2022 or 2023. The program, controversial since its inception, has suffered setbacks due to congressional pressure.

The Navy’s 2016 Fiscal Year (FY) budget to Congress will include these stipulations, among others. The budget will ask for $135 million in funding for the program, which is a considerable drop from the $403 million requested in the 2015 FY budget. The program has come under scrutiny from Congress, which in 2014 demanded that the Navy submit consistent reports and studies to Congress before further funding can be provided. UCLASS’s capabilities are currently being tested by a comprehensive information, surveillance and reconnaissance (ISR) review conducted by the Department of Defense.

“Work on the other UCLASS segments, such as the carrier segment and the control system and connectivity segment, associated programs of record, such as stand up of the integration labs and test facilities, continues throughout the requirement and review process in order to reduce cost and mitigate overall program risk,” said Rear Adm. William Lescher, the Deputy Assistant Secretary of the Navy for Budget.

The Navy had originally intended UCLASS to provide long-range lethal capabilities that are currently provided by manned carrier fleets. However, due to concerns expressed by military and government officials, the Navy now wants the program to focus more on intelligence gathering and refuelling missions. Limited strike capabilities are also being considered.

“The Navy may have made an appropriate set of trade-offs between costs and capabilities in deriving a set of requirements for UCLASS,” says a congressional report, “but those trade-offs should be evaluated in the context of the overall CSG capability, not on the basis of individual capabilities of weapons systems or an unconstrained budget.”

In 2014, the Navy had intended to issue RFPs directly to Lockheed Martin, Northrop Grumman, General Atomics, and Boeing for the entire UCLASS program. Due to objections from Congress, however, they had to scrap the RFPs. Yet Sean Stackley, Assistant Secretary of the Navy for Research, Development and Acquisition, claims that the Navy feels confident that the Department of Defense has conducted enough research to allow the Navy to send out RFPs for the UAVs themselves in 2016.

“We did an extensive portfolio review on unmanned — not just UCLASS — in the fall review as part of the budget process,” Stackley said. “There’s more work to be done and that will continue on into this calendar year as we prepare for [the 2017 budget request].”