ANCHORAGE, Alaska (AP) — Royal Dutch Shell PLC has filed a revised Arctic offshore drilling plan with federal regulators but says the company hasn’t decided whether to return to waters off the coast of northwest Alaska in 2015.

The revised exploration plan submitted to the Bureau of Ocean Energy Management in Anchorage calls for two drilling vessels to operate simultaneously in the Chukchi Sea rather than one in the Chukchi and one in the Beaufort Sea off Alaska’s north Coast.