WASHINGTON (AP) — A top aide to President Barack Obama says the White House’s classified computer systems are secure while acknowledging vulnerabilities in its unclassified system.

The comments come in response to a CNN report Tuesday that Russian hackers got access to sensitive White House information such as the president’s private schedule.

The White House acknowledged in October that it detected suspicious activity on its unclassified network while assessing possible cyberthreats.

Obama adviser Ben Rhodes would not confirm CNN’s report that sensitive information was accessed or comment on where the threat originated.

But he says, “There’s always vulnerability.” Rhodes says that’s why the White House operates a separate, secure system for classified data.

He says the White House takes regular actions to prevent intrusions on its unclassified network.