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Mr Sullivan reportedly asked the man to leave and was left unharmed

By Madeline Halpert

BBC News

The US Secret Service is investigating a break-in at the home of National Security Advisor Jake Sullivan.

Officials are looking into how an apparently intoxicated man was able to break into Mr Sullivan's home, evading security agents stationed outside, according to BBC's US partner CBS News.

The intrusion took place last month, a US law enforcement official said.

The man - who is still at large - reportedly walked into Mr Sullivan's home around 03:00 EDT (08:00 BST).

Mr Sullivan confronted the intruder - who did not appear to know Mr Sullivan or have an intention of harming him - and asked him to leave, according to the Washington Post.

More than two Secret Service agents were parked outside and were not aware of the break-in until Mr Sullivan told them about it, a US law enforcement official told CBS.

The agency has launched an investigation into how this happened, the Secret Service said in a statement. "While the protectee was unharmed, we are taking this matter seriously and have opened a comprehensive mission assurance investigation to review all facets of what occurred."