President Trump’s longtime security guard will reportedly be grilled by congressional investigators over a 2013 trip that Trump took to Moscow.

Keith Schiller, a former security chief for the president, will be questioned about the Russian excursion which is at the center of salacious allegations included in a dossier about the president, according to The Washington Post (paywall).

The House Intelligence Committee is asking Schiller to appear for an interview Tuesday as part of its probe into Russian interference in the 2016 presidential election, the paper said.

The 35-page dossier produced by British intelligence officer Christopher Steele details behavior by Trump while he visiting Moscow for the 2013 Miss Universe pageant.

Trump has called the dossier “phony stuff.”