Upon graduation from the United States Naval War College, he assumed command of the 3rd Brigade, 3rd Infantry Division (Mechanized).
In 2004 and 2005, he was appointed to Commander and Senior Military Representative of NATO headquarters in Sarajevo, Bosnia and Herzegovina.
[3] Schook succeeded Lawrence Rossin in that position and worked under SRSG Søren Jessen-Petersen and Joachim Rücker.
[2] In 2007, Schook came under investigation by the United Nations Office of Internal Oversight Services (OIOS), in response to rumours and allegations including on aggressive behavior, and unprofessional and close relationships with Kosovan Energy Minister Ethem Çeku.
[4] According to German news magazine Der Spiegel, OIOS also investigated reports that Schook had disclosed the location of a man in a UN witness protection program, who had testified against Ramush Haradinaj.