And who is a 'suspected terrorist? Anyone the government says is a 'suspected' terrorist.
"In any case in which the Attorney General has denied the transfer of a firearm to a prospective transferee pursuant to section 922A or has made a determination regarding a firearm permit applicant pursuant to section 922B, an action challenging the determination may be brought against the United States. The petition must be filed not later than 60 days after the petitioner has received actual notice of the Attorney General’s determination made pursuant to section 922A or 922B. The court shall sustain the Attorney General’s determination on a showing by the United States by a preponderance of evidence that the Attorney General’s determination satisfied the requirements of section 922A or 922B. To make this showing, the United States may submit, and the court may rely on, summaries or redacted versions of documents containing information the disclosure of which the Attorney General has determined would likely compromise national security. On request of the petitioner or the court’s own motion, the court may review the full, undisclosed documents ex parte and in camera. The court shall determine whether the summaries or redacted versions, as the case may be, are fair and accurate representations of the underlying documents. The court shall not consider the full, undisclosed documents in deciding whether the Attorney General’s determination satisfies the requirements of section 922A or 922B.’."
They have already started compiling the list -- 'militia' members, 'disgruntled' military veterans, and 'rightwing extremists' -- to name a few. See the Missouri Analysis and Information Center (MIAC) and Department of Homeland Security reports.