The Justice Department will appeal a court ruling that allowed the merger between AT&T and Time Warner. In court records released today, the agency said it plans to take the lower court’s decision to the DC Circuit Court of Appeals, in another attempt to block the deal.

Last month’s decision against the Justice Department was a severe rebuke of the Trump administration’s antitrust enforcement team, and it allowed for the creation of a major new player in the telecom industry. The judge’s ruling, moreover, was an extraordinarily one-sided decision in favor of the merger, although the legal thinking behind that ruling was controversial. It was unclear whether the department would decide to bring the appeal in the face of the judge’s stern decision.

The merger, which combined AT&T’s pay-TV business with content like HBO and Warner Bros., also provided a regulatory green light for similar deals: the next day, seeing the ruling in favor of the companies, Comcast announced a play for 21st Century Fox.

The department previously said it would allow the deal to move ahead as it considered whether to appeal, and the two companies officially combined shortly after, just ahead of a deadline to finalize the merger. While the deal has closed, a successful appeal could theoretically still unwind that merger.

AT&T has meanwhile moved full-steam ahead with its plans, holding discussions on what to do with newly acquired properties like HBO.

The Justice Department did not provide a comment beyond the brief court filing.

“The Court’s decision could hardly have been more thorough, fact-based, and well-reasoned,” AT&T general counsel David McAtee said in a statement. “While the losing party in litigation always has the right to appeal if it wishes, we are surprised that the DOJ has chosen to do so under these circumstances. We are ready to defend the Court’s decision at the D.C. Circuit Court of Appeals.”