The Obama administration’s best argument for the Iran nuclear deal is also an argument against its general enthusiasm for multilateralism in preserving the international order. If a deal with Iran were not struck soon, it is indeed quite possible that the coalition imposing sanctions on Iran would unravel. And there is no chance that this coalition will ratchet sanctions up to put more pressure on Iran. The coalition may be fraying even more quickly now, as Russia and China fall into financial distress and become more eager to export goods to Iran. Russia in particular supported Iran in its demand to have restrictions on development of ballistic missiles lifted. No prizes for guessing what nation is likely to make money off deals with Iran in that area.
But this line of analysis is also a demonstration of the inherent weakness of international coalitions as an instrument of foreign policy. Nations may come together to purse a joint program, when their interests coincide. But the world is a turbulent place and interests change. And unlike domestic contracts, long term agreements among nations are difficult to police and enforce.
That is the reason that United States would do well to maintain the force and will to act alone.