While the Allies remain committed to collective defence, they have increasingly endowed NATO with new roles as an instrument of collective security in the Euro-Atlantic region. Elements of Partnership for Peace (PFP), the May 1997 NATO-Russian Founding Act, the stabilisation commitment in post-war Bosnia and other activities have raised new challenges for NATO's cohesion and effectiveness: how to give practical content to its vision of a peaceful political order in Europe; how to handle the hypothetical issue of eventual Russian membership in the Alliance; what meaning to attribute to vague 'security is indivisible' declarations and the Article 4-like security-consultation commitments offered to PFP members; and how to maintain collective defence in good order while assuming collective-security duties.