U.S. Congressional Aides’ visits to North Korea’s industrial complex in March and May have been confirmed.

A source specializing in North Korea said a group of about ten aides representing both Democratic and Republican congressmen visited the Gaeseong complex on March 21st and May 30th.

The source said the aides visited South Korean companies operating in the complex and were briefed on factory conditions.

Pyongyang's admittance of U.S. aides in May is drawing particular attention since ties between two Koreas were strained at the time.