WASHINGTON » The White House says President Barack Obama does not have the authority to use a drone to kill a U.S. citizen on American soil if the citizen is not engaged in combat.

Obama spokesman Jay Carney says the attorney general made that assertion in a letter to GOP Sen. Rand Paul. The Kentucky senator has held up the nomination of John Brennan as CIA director amid claims that the administration could use drones to target Americans suspected of terrorism.

Carney says Attorney General Eric Holder sent the letter to Paul this afternoon, though the senator’s office says it has yet to receive it. Carney says White House officials have also been in touch with Paul’s office.