Lodewijk (Lo) Casteleijn (1948) is Senior Research Associate at the Clingendael Institute. From 2000 until 2011 Casteleijn was Principal director of the Department for General Policy Affairs at the Ministry of Defence of the Netherlands, where he served from 1982 onwards. He started his career as an assistant to the Dutch Labour Party's Parliamentary Group in the Hague, and was political assistant to the minister of Foreign Affairs.
Lo Casteleijn has for many years advised the Dutch ministers of Defence on all aspects of Security and Defence policy. He was responsible for the drafting of Defence White Papers and other policy documents, and for parliamentary affairs. He specialized in the areas of Nato, the Common Security and Defence Policy (CSDP) of the EU, nuclear and proliferation issues, crisis management and the political aspects of international military operations. Lo Casteleijn led Dutch delegations to international meetings of Nato and EU. He was the European co-chairman of Nato's Defence Group on Proliferation (1999-2000) and of Senior Officials' Groups on Nato's military command structure (2003) and on the financial and planning arrangements of Nato (2010-2011).
Lo Casteleijn studied Political Science at the University of Amsterdam.
Expertise: Dutch and International Security and Defence Policy, Nato, Common Security and Defence Policy (EU).