What we can expect from the historic trial, from the key players to unusual rules in place.Read more
The Republicans and Democrats have very different views on the upcoming trial.
The FBI says FaceApp and other mobile applications developed in Russia pose a "potential counterintelligence threat".
The comments were made in a letter to US Senator Chuck Schumer after he called for an investigation into the app.
The face-editing tool went viral earlier this year but prompted privacy concerns.
The FBI comments come amid rising US concern that products made by foreign tech firms could pose security risks.
In a letter addressed to Mr Schumer, the agency said "it considers any mobile application or similar product developed in Russia, such as FaceApp, to be a potential counterintelligence threat".