BISMARCK, N.D. (AP) – Two Sioux tribes suing over the Dakota Access pipeline say they're willing to put their claims on hold while the Army considers whether to allow the pipeline to cross under a Missouri River reservoir in North Dakota.

The Army on Sunday declined to approve an easement for the crossing, citing a need for more study and consideration of alternative routes.

Dallas-based Energy Transfer Partners believes it already has the necessary permission and has asked a federal judge to concur.

The Standing Rock and Cheyenne River tribes are challenging pipeline permits at numerous water crossings. They say in court documents that they're willing to suspend the litigation during the study process. The tribes also intend to oppose ETP's request to the judge for permission to drill under the lake.