Three U.S. service members detailed to President Donald Trump are under investigation for allegations that they may have violated U.S. security procedures during the president’s trip to Vietnam, the Pentagon confirmed late Tuesday.

The service members were assigned to provide communications and other support to the president during his 12-day trip through Asia, which included a stop in Vietnam, Pentagon spokesman Mark Wright said.

The allegations, first reported by the Washington Post, would be the second reported incident of service members assigned to the high-profile positions of providing communications and security for the president choosing to violate security protocol instead.

In August, four military members of Vice President Mike Pence’s communications team were reassigned following an investigation that found they had brought foreign women into a secure area as they did the advance work for Pence’s trip.

The service members are under investigation for allegations that they had similar contact with foreign women while in Vietnam.

“We are aware of the incident, and it is currently under investigation,” said Pentagon spokesman Mark Wright.