Sean Plankey, the Department of Homeland Security senior adviser and Trump nominee to lead the Cybersecurity and Infrastructure Security Agency, was escorted out of the U.S. Coast Guard headquarters late Monday and had his access badge removed, according to sources familiar with the matter. The nominee to lead the cyber defense agency has left his role at DHS, though circumstances behind the sudden move remain unclear.Plankey, a retired U.S. Coast Guard officer, formerly served as senior adviser to the homeland security secretary for the Coast Guard, a role he held while awaiting Senate action on his nomination to lead CISA, the agency responsible for protecting federal civilian networks and U.S. critical infrastructure from cyber threats.A Coast Guard spokesperson referred inquiries to DHS. "We have no personnel matters to announce at this time," a DHS spokesperson said. CBS News has also reached out to CISA for comment. Florida Sen.…