U.S. Department of Homeland Security issued the following announcement on May 15.
Under 49 U.S.C. § 44907 Acting Secretary of Homeland Security Kevin K. McAleenan determined that conditions in Venezuela threaten the safety and security of passengers, aircraft, and crew, requiring an immediate suspension of all commercial passenger and cargo flights between the United States and Venezuela. In accordance with the statute, the Secretary of State has approved flight suspension, and the Secretary of Transportation has implemented the determination.
This determination is based on the ongoing political instability and increased tensions in Venezuela and associated inadvertent risk to flight operations.
In coordination with the Department of State and the Department of Transportation, the Department of Homeland Security will continue to monitor this situation. If and when the conditions in Venezuela change, and if in the public interest, the Secretaries will revisit this determination. Until then, the flight suspension will remain in effect indefinitely.
Original source can be found here.