The FBI gained approval from a secret federal court last summer to conduct communications surveillance against Carter Page, a former adviser to Donald Trump’s presidential campaign, The Washington Post is reporting.

The revelation confirms for the first time that a federal surveillance warrant, known as a FISA warrant, was issued for a member of the Trump campaign as part of a federal investigation of potential ties between the Republican’s associates and the Russian government.

In the application for the warrant, federal officials laid out what they said was evidence that there was probable cause showing that Page was acting as an agent of the Russian government, officials told The Post.

That evidence included contacts in 2013 with Russian spies who tried to recruit Page in New York City. The details of that recruitment attempt were laid out in a sealed FBI complaint filed in Jan. 2015. BuzzFeed News published the complaint earlier this month. Page denied that he was successfully recruited or that he shared any sensitive information with the agents.