Makan Delrahim, assistant attorney general for the antitrust division at the U.S. Justice Department, questioned the effectiveness of behavioral conditions amid mounting antitrust concerns over the Comcast-NBCUniversal merger.

Delrahim visited CNBC’s “Squawk Box” to discuss several regulatory topics and was asked how he would respond to a tweet from President Donald Trump pointing out Comcast’s possibly anticompetitive behavior. Delrahim said since the behavioral conditions placed on that merger expired in September, the DOJ has remained vigilant for any potential antitrust violations on the part of Comcast.

“You know, I have—one of the things I’ve been both criticized and, I think, praised for is that I don’t believe these behavioral consent decrees as a solution to these mergers. We come in and tell a company to withhold its natural tendencies, its natural incentives to make a profit and then they evaporate after five, seven, 10 years. And it makes no sense. Because seven years before we’re trying to guess where the market is. I believe in structural solutions. That’s what we’ve suggested,” Delrahim told “Squawk Box.”

Delrahim’s new comments don’t deviate far from what he wrote in a letter to Comcast in August, asking the company to disclose any changes it might make after the conditions expire.

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“We would appreciate your cooperation in keeping us informed by providing the department with any plans you may have to change your policies or practices involving video programming and distribution,” Delrahim wrote.

However, the DOJ could now be considering a call from the American Cable Association to launch an antitrust investigation into Comcast-NBCU.

"By opening a formal investigation, the DOJ, which has already put Comcast-NBCU on notice, can take the next step to gather facts about the company's activities and ensure consumers and competition are protected. Given the enormity of Comcast-NBCU's market presence and incentive to engage in anticompetitive harm, such an investigation is fully warranted," said ACA President and CEO Matthew M. Polka in a statement.