Updated at 4:21 p.m. Jan. 9

WASHINGTON — For the third time in nine months, a defendant in a lawsuit challenging the U.S. Air Force’s $11 billion bulk purchase of rockets from United Launch Alliance are asking a federal judge to dismiss the case.

In April, SpaceX asked the U.S. Court of Federal Claims to void a large portion of the sole-source deal, which was signed in 2013 and includes 36 rocket cores from ULA.

Hawthorne, California-based SpaceX, whose Falcon 9 rocket is undergoing Air Force certification to launch national security payloads, argues that it should have been given the opportunity to bid on a large number of those missions.

The Justice Department, which is representing the Air Force in the lawsuit, or ULA, which has intervened as a defendant in the case, filed its latest motion to dismiss Jan. 7, according to the electronic court document system known as the Public Access to Court Electronic Records, or PACER. It is unclear exactly who filed the motion because it is under seal, as have been most new documents in the case since the presiding judge, Susan Braden, put media gag orders on all involved parties in July.

Nicole Navas, a spokeswoman for the Justice Department, declined to comment.

Previously, the Justice Department asked the court to dismiss the suit in June, claiming SpaceX missed its window to appeal the contract, and then again in November, challenging the court’s jurisdiction on the matter.