Stability could have been ensured without a military alliance like NATO. The European Union could have managed to create stability on its own, the EU itself since the Lisbon Treaty has gained the role of the West European Union security organisation. Additionally admission to NATO (and incidentally the EU) require social harmonisation and stability to occur before a new state can join, to quote the NATO Handbook directly; “States which are involved in ethnic disputes or external territorial disputes, including irredentist claims, or internal jurisdictional disputes, must settle those disputes by peaceful means in accordance with OSCE principles, before they can become members.” [1] If these nations had to sort out their problems first what was the point of enlargement, it is not enlargement per se that is meaning that these disputes are solved.  [1] NATO, The NATO Handbook; The 1995 Study on NATO's Enlargement, 1995,