The chief State Department official who oversaw the response to the “Havana syndrome" has left her role after six months at the post, a department spokesperson confirmed to The Hill Thursday.

Ambassador Pamela Spratlen was appointed by the Biden administration to oversee the State Department’s response to incidents in which overseas diplomats and officials have reported feeling strangely ill, though the cause is not clearly understood, NBC News reported.

“Ambassador Spratlen earlier this year agreed to return to the Department to take on the role, created by Secretary [Antony] Blinken, of Senior Advisor of the Health Incidents Response Task Force (HIRTF). A retired Ambassador, Ambassador Spratlen did so as a Reemployed Annuitant (REA) and recently reached the threshold of hours of labor permitted under REA status.  We thank her for her service and invaluable contributions to the efforts of the Task Force. We expect to name her replacement soon,” the spokesperson told The Hill in a statement.

“As part of the National Security Council-led interagency response effort and in coordination with our partners across the U.S. Government, we are vigorously investigating reports of possible [cases] wherever they are reported,” the spokesperson added. “The interagency is actively working to identify the cause of these incidents and whether they may be attributed to a foreign actor, and is focused on providing care for those affected.”

Earlier this month, Defense Secretary Lloyd Austin sent a memo to service members, contractors and civilian employees urging them to report “anomalous health incidents” — noting that possible symptoms included pain, nausea and headaches in response to heat, pressure and sounds.

The cause of “Havana syndrome” is not yet clear, but cases first became known when U.S. officials started to feel strangely ill while at the U.S. Embassy in Cuba in 2016. Some think that U.S. adversaries are behind the painful effects, using radio wave weapons. Up to 200 Americans have reported possible cases associated with the syndrome.

The announcement comes as some diplomats have expressed frustration at the way that U.S. officials have responded to research and reports related to the syndrome. Earlier this month, Blinken was on a call with U.S. diplomats who had “Havana syndrome,” where diplomats expressed their frustration that their symptoms were not being taken seriously enough.

A State Department spokesperson told The Hill in their statement that “In a recent call to affected employees, Secretary Blinken emphasized the priority he attaches to this issue as part of his focus on ensuring the safety and security of the workforce and their families. As he expressed to the full workforce, the Secretary stressed that we will continue to focus on keeping the workforce informed, seeking answers, and providing support to those affected.”