The Biden administration is letting Alaska Airlines complete its $1 billion purchase of Hawaiian Airlines after the carriers agreed to certain conditions, including maintaining maintain current service on routes between Hawaii and the mainland U.S. where they don’t have much competition.

Transportation Department officials said Tuesday that no obstacles remain to the airlines closing their $1 billion deal and beginning to merge, although some final approvals are still pending.

Transportation Secretary Pete Buttigieg said the airlines made promises to protect travelers, including upholding the value of frequent-flyer rewards.

The decision to clear the way for the airlines to close their merger stands in contrast to the administration's adamant opposition to previous airline deals. The Justice Department successfully sued to block JetBlue's attempt to buy Spirit Airlines.

The Justice Department could still challenge the Alaska-Hawaiian deal, but that appears unlikely.