Is power of veto vital to international cooperation?

The UN Security Council has been the subject of wide-ranging debate about whether it should open its doors to other permanent members. Many countries wish to join this select group to gain the power of veto that goes along with membership. Because of the inequalities it introduces and its ability to obstruct negotiations, veto power has been a tricky issue so far. Yet it may also be vital to international cooperation, to counteract the existing balance of power between nations.