The purpose of this study is to analyse policy changes between the intelligence and security organisations in Denmark, Switzerland, UK and Germany seen against the terrorist attacks against the US on the 11th of September 2001. Denmark and Switzerland respectively have a military intelligence service and a security service. In both cases, military intelligence is subordinated to the ministries of defence, while the security services constitute parts of the national police authorities, which is subordinated to the Ministry of Justice. The UK has two intelligence services under the Ministry of Foreign Affairs and a security services belonging to the Home Office, while Germany has an intellligence services which constitutes a part of the Defence Forces and a security service directly subordinated to the Bundeskanzler and the federal government. In Denmark the intelligence as well as the security service has been allotted increased resources and mandate. Facilitated cooperation between these services and to other emergency authorities has been a priority, as well as the creation of a common centre for analysis. The same pattern can be seen in Switzerland, but implemented with less success, no significant changes have so far been accomplished. Swiss bank secrecy constitutes an institution worthy of protection, but also one of potential vulnerability. Switzerland has bilateral agreements with the US in the fight against Al Qaida. The UK has increasingly focused on domestic security and the three intelligence agencies have joined in a combined analytical counter-terrorism centre, JTAC, which has become the most important instrument against international terrorism. The security service has the lead in the fight against terrorism. In Germany, neither central nor military intelligence has been significantly affected by the terrorist threat. The security service has however received increased mandate and resources. The most important change is the creation of a joint centre for counterterrorism, resembling the British JTAC, and a new law, allowing the sharing of data bases between authorities. The UN and EU have through resolutions and conventions to a certain extent set the agenda in counterterrorism affairs, which partly explains the similarities in the analysed countries. One significant pattern is the leading role of the security services egarding counterterrorism. Another is that the field of intelligence has widened and the creation of joint analytical centres. Even through the overall picture is common, there exist differences in the perception of international terrorism, which has repercussions on how priorities are formed. Is the threat internal, external or global; directed at the own country or not? Experiences of accomplished terrorist acts, not least after 9/11, can to a certain extent explain these differences in nuance. The 9/11 effect is furthermore apparent in the transformation of the policy area. There is however reason to believe that policy problems appeared earlier and that the attack became a window of opportunity to propel change. Further research should focus on the process of change in greater detail, to be able to establish the actual pace as well as the depth of change. The role of institutional design should be another subject for research, in order to analyse its role for capacity of adjustment in this policy domain.