TOKYO (AP) — Boeing said Friday it sees commercial flights of its grounded 787 jets resuming "within weeks" even though it has not pinpointed the cause of battery overheating.

Boeing Co. Chief Project Engineer Michael Sinnett outlined a fix centered on a new design for the lithium-ion battery system that has layers of safeguards to prevent overheating and measures to contain malfunctions.

"We could be back up and going in weeks and not months," Sinnett told reporters at a Tokyo hotel. A third of safety tests have already been completed. A Japanese official said it was possible flights could resume next month.