Commander Kai Vittrup started his professional life in the Uniform Branch of Copenhagen Police on 1 April 1965. From 1965 until 1970, he attended police basic training, receiving a diploma for outstanding performance. After more than 41 years in action, Commander Vittrup performed several functions in the Uniform Branch, such as Detective Constable; Police Platoon Leader; Duty Officer; Chief Inspector; Deputy to the head of Gladsaxc Police; head of the National Commissioner's Tactical Support Unit; observer and supervisor of defense, anti-terrorist and disaster exercises; head of Aalborg Uniform Branch; and Chief of Copenhagen Police Uniform Branch.

Responsible for many relevant assignments and tasks, Brig Gen Vittrup developed a training manual of tactical principles for police operational command functions in wartime, a Police College training manual in disaster and disaster area command functions, the first police training manual in staff duties, streamlined the police emergency plan for crisis and times of war, drew up a general and simplified police staff handbook, developed new concepts for dealing with riot and crowd violence control adopted by many countries in Europe, and in 1999 finished three books on police strategies, police operations, police tactics and logistics, which are being used at the Police Senior Leadership and Management Course and other important courses.

In his international experience, Brig Gen Vittrup was tasked in 1992 for UNPROFOR, Sarajevo, attended in 1996 the NATO School Shape and NATO Civil Emergency Planning/Civil Military Cooperation (CEP/CIVMILC) course. In 2000, he was attached to the UNTAET in East Timor as Senior Security Adviser. Afterwards, he was responsible for several lectures for high-ranking police officers in riot and crowd control in Gaza, The West Bank, Albania, Estonia and Latvia. In 2003 and 2004, he was appointed as Regional Senior Security Adviser in Iraq, dealing with the Iraqi Police in the field of training, monitoring, mentoring and logistics. In October 2004, he was appointed as Police Commissioner in UNMIK, Kosovo.

Gen Brig Vittrup came to UNMIS in September 2006, and quickly introduced new strategic actions, including Targeted Monitoring, Pro-active Collocation and Assisted Cyclical Training, developed to assist the particular necessities of each specific location. These actions brought into UNMIS Police performance a fabulous improvement and yielded excellent results within a short time.