NEW YORK

The Secret Service has launched an investigation into how an intruder was able to enter White House national security adviser Jake Sullivan's home, US media reported Tuesday. 

The intrusion happened in the middle of the night in late April and Sullivan was unharmed, Secret Service spokesman Anthony Guglielmi said in a statement.

Sullivan confronted the intruder, who appeared to be intoxicated, and told him to leave, according to media reports citing officials.

"We are taking this matter seriously and have opened a comprehensive mission assurance investigation to review all facets of what occurred," said Guglielmi.

"Any deviation from our protective protocols is unacceptable, and if discovered, personnel will be held accountable. Modifications to the protective posture have also been made to ensure additional security layers are in place as we conduct this comprehensive review."