The Justice Department said it should have discontinued its surveillance of Trump campaign adviser Carter Page earlier than it did in a court filing unsealed on Thursday, according to The Wall Street Journal. In a December letter to the Foreign Intelligence Surveillance Act court, which issues warrants and oversees surveillance of suspected foreign spies, the department said it lacked probable cause to continue its surveillance of Page in two warrant renewals in 2017. Surveillance of Page began in late 2016, after he had left the campaign. The DOJ said it would isolate the material collected from the surveillance effort until an internal review on the matter was completed. The department has not spoken publicly on the matter.

This comes after allegations, posited by President Trump himself, that his campaign was spied on. In a report last year, Justice Department Inspector General found “at least 17 significant errors or omissions” in applications to surveil Page—but also concluded the FBI had sufficient evidence to launch a counter-intelligence probe against Trump’s associates.