HOUSTON — NASA said Tuesday that Boeing's Starliner spacecraft would not return to crewed service before 2027, extending the agency's dependence on SpaceX's Crew Dragon for International Space Station missions. The announcement followed continued analysis of propulsion problems.

Boeing's CST-100 Starliner has faced repeated setbacks since its 2024 crewed test flight, when helium leaks and thruster failures forced NASA to return its astronauts aboard a SpaceX capsule. Engineers at NASA and Boeing have since worked to redesign parts of the propulsion system before certifying the vehicle.

NASA said it was still evaluating whether Starliner's next flight would carry cargo or crew, with a final decision depending on completing thruster testing. Hardware qualification work is ongoing at facilities in New Mexico and Florida.

The delay carries commercial and strategic weight. NASA has sought two independent providers for crew transport to reduce reliance on a single company, but SpaceX has flown the overwhelming majority of missions since 2020. Continued Starliner delays raise questions about the program's cost, which Boeing has already absorbed through more than $2 billion in charges.

NASA said it remained committed to certifying Starliner to preserve redundancy in low Earth orbit access. "We continue to work with Boeing toward a safe return to flight, and we will fly when the vehicle is ready," a NASA spokesperson said in a statement.