Andrew Peek, a senior director for European and Russian affairs at the National Security Council (NSC), has been forced into administrative leave amid a pending security investigation. He was escorted out of the White House on Friday.

Peek, formerly the deputy assistant secretary of state focusing on Iraq and Iran, began the role in November. His predecessors — Fiona Hill and Tim Morrison — both testified in the ongoing impeachment of President Trump.

The reason for Peek’s sudden departure remains unclear, with the NSC telling news outlets “we do not discuss personnel matters.” It’s also unknown whether Peek’s departure could be connected to the ongoing Ukraine scandal.

Peek was expected to attend the World Economic Forum conference in Davos, Switzerland, this week.

Peek had also served as a U.S. Army Intelligence adviser to Marine Gen. John Allen, who is now retired. Gen. Allen had led the International Security Assistance Force (ISAF) which fought the Taliban insurgency in Afghanistan and helped the country rebuild its government institutions.

According to the State Department’s website, Peek served as a foreign affairs adviser for two Republican senators and is a Ph.D. candidate at the Johns Hopkins School of International Studies. He also holds a Master's from the Harvard Kennedy School of Government.