President Donald Trump signed three executive orders Friday regarding the use of drones and other aviation technologies. White House officials said the orders are in direct response to a string of bizarre sightings along the East Coast last year.

The risks of drones have been underscored by Russia's drone strikes in Ukraine, and Ukraine's surprise drone strikes that destroyed some aircraft deep within Russia, the White House said.

President Trump also eased restrictions on commercial drone flights and called for the revival of supersonic flights for nonmilitary aircraft.

Donald Trump said on Saturday his relationship with his billionaire donor Elon Musk is over and warned there would be "serious consequences" if Musk funds U.S. Democrats running against Republicans who vote for the president's sweeping tax and spending bill.

Trump warns his former ally against backing any Democratic candidates to challenge the Republicans, as a messy feud between the two escalates.

U.S. President Donald Trump, in an interview with NBC News on Saturday, said there would be "serious consequences" if billionaire Elon Musk funds Democratic Party candidates to run against Republicans who vote for Trump's sweeping tax-cut bill.