The United States says it is working to diplomatically resolve North Korea’s detainment of two American journalists.

State Department spokesman Robert Wood told reporters Monday the North has confirmed that it’s holding two Americans pending an investigation. He added that the U.S. is working on the issue diplomatically.

However, Wood stopped short of elaborating on how the confirmation was received from Pyongyang, saying the details were “very sensitive.”

Laura Ling and Euna Kim, reporters for the online media outlet Current TV, were detained in North Korea last Tuesday for, what the North says was “an illegal intrusion into its territory” and are now reportedly in Pyongyang undergoing an investigation.