In a press release, the government announced that they have decided to appoint Thomas Nilsson as the head of the Swedish Armed Forces' Military Intelligence and Security Service, Must. He is simultaneously promoted to lieutenant general.

Thomas Nilsson has been appointed as the head of Must from 1 May 2023 until further notice, but no later than 30 April 2027. He replaces Major General Lena Hallin, whose appointment ends on 30 April 2023.

– Thomas Nilsson has a broad background in Swedish defence and extensive experience in international cooperation from his previous role as Sweden's military representative to the EU and NATO. The intersection of technology, security policy, and intelligence will be even more important in the future, and therefore it is very positive that Thomas Nilsson has chosen to undertake this important assignment, says Minister of Defence Pål Jonson in the announcement on the government's website.

Must is a part of the Swedish Armed Forces and conducts defence intelligence activities and military intelligence and security services. Must's mission includes identifying, assessing, and countering external threats to Sweden and Swedish interests abroad while also supporting the government and the Supreme Commander.

The press release states that Thomas Nilsson has his background in the Swedish Armed Forces and the Air Force. Between 2016-2020, Thomas Nilsson served as Sweden's military representative to the EU and NATO in Brussels. In 2020, Thomas Nilsson was appointed as the Swedish Armed Forces' Chief Information Officer (FM CIO) and was promoted to major general.