SpaceX CEO Elon Musk said today that his company will file a suit against the U.S. Air Force’s decision to award a large bulk buy of 36 core boosters to rival United Launch Alliance (ULA). Musk said that the suit is aimed at forcing the U.S. Air Force to open the launches for competition.

Musk said that the certification process that the U.S. Air Force is requiring of SpaceX’s Falcon 9 booster is essentially a “paperwork exercise” in which no changes have been required to the rocket.

The SpaceX founder claimed that ULA’s rockets are four times more expensive than SpaceX’s booster. He also attacked the idea of ULA relying on Russia’s RD-180 engine to power the first stage of its Atlas V booster at a time when tensions have spiked over Russia’s annexation of Crimea and its threats against Ukraine.

Musk said he does not know why ULA’s rockets are so expensive. But, he said that SpaceX has made a lot of innovations in its booster and production process while ULA is burdened with a lot of legacy hardware.

SpaceX is seeking to have the 36-core contract canceled and a new competition initiated in which SpaceX can compete with its Falcon 9 and Falcon Heavy boosters.