The shady dealings of Donald Trump associate Carter Page with Russian officials set off significant enough alarm bells in the U.S. intelligence community that the FBI sought and was granted permission from a Foreign Intelligence Surveillance Court judge to monitor the communications of the Trump adviser as far back as July 2016, the Washington Post reported Thursday evening. Page was the only American a FISA court has granted the government permission to eavesdrop on as part of the probe into Russia’s election meddling, officials told the Post. The 90-day FISA warrant to surveil Page was renewed at least once.

Page, for his part, has denied any wrongdoing and the Trump administration has attempted to distance itself from the early Trump supporter and foreign policy adviser. “During an interview with the Washington Post editorial page staff in March 2016, Trump identified Page, who had previously been an investment banker in Moscow, as a foreign policy adviser to his campaign,” the Post notes. “Campaign spokeswoman Hope Hicks later described Page’s role as ‘informal.’” The whole Trump campaign apparatus, however, was pretty informal by modern campaign standards.

Page has significant Russian ties from his time in Moscow working for Merrill Lynch a decade ago; he also has had financial ties to the Russian energy firm Gazprom. Russian intelligence was aware of Page and, according to court documents, tried to cultivate him as an intelligence source as far back as 2013. Page’s affinity for Moscow and his praise for Vladimir Putin worried the foreign policy establishment as Trump surged to the top of the Republican ticket. Page’s sketchy associates and shadowy business dealings were enough to lead U.S. investigators to look deeper. While the application for a FISA warrant is not an absolute indicator of guilt, the bar for granting surveillance powers is substantial. From the Post:

The judges who rule on Foreign Intelligence Surveillance Act (FISA) requests oversee the nation’s most sensitive national security cases, and their warrants are some of the most closely guarded secrets in the world of U.S. law enforcement and intelligence gathering. Any FISA application has to be approved at the highest levels of the Justice Department and the FBI.

The government’s application for the surveillance order targeting Page included a lengthy declaration that laid out investigators’ basis for believing that Page was an agent of the Russian government and knowingly engaged in clandestine intelligence activities on behalf of Moscow, officials said. Among other things, the application cited contacts that he had with a Russian intelligence operative in New York City in 2013, officials said. Those contacts had earlier surfaced in a federal espionage case brought by the Justice Department against another Russian agent. In addition, the application said Page had other contacts with Russian operatives that have not been publicly disclosed, officials said.

“I have nothing to hide,” Page told the Post, who then went on to compare his surveillance to that of Martin Luther King Jr. by the FBI and Justice Department during the civil rights movement.