I think that one needs strong economic ties, but it seems to only truly work with democratic societies.
Economic interdependence is a deterrent against war, not an absolute barrier.
If you can easily swap trade partners for example, it's less of a deterrent. Which is one of the reasons why EU has gone beyond simple import/export agreements.
If a Member State is the victim of armed aggression on its territory, the other Member States shall have towards it an obligation of aid and assistance by all the means in their power, in accordance with Article 51 of the United Nations Charter. This shall not prejudice the specific character of the security and defence policy of certain Member States.
Commitments and cooperation in this area shall be consistent with commitments under the North Atlantic Treaty Organisation, which, for those States which are members of it, remains the foundation of their collective defence and the forum for its implementation.
Wasn't that NATO (aka mostly the US)?