What the law covers
The Justice Department says the Foreign Agents Registration Act generally requires disclosure when a person acts in the United States at the order, request, direction or control of a foreign principal and engages in covered political, public-relations, fundraising or government-representation activities.
FARA also contains exemptions, including some bona fide commercial activity and certain lobbying properly registered under the Lobbying Disclosure Act. The existence of a foreign investor, customer or diplomatic contact therefore does not automatically make someone a foreign agent.