Most now assume that the defining foreign policy legacy of President Obama will be his Iran deal, which will seek to block Iran's path to a nuclear weapon and open the doors to Iran's reintegration into the world economy and regional politics. I believe Obama and good sense will prevail over the Israel caucus in Congress, and as a result of the deal Americans will fairly soon come to see Iran both as a market for American goods and ideas and as a valuable ally against ISIS, the Sunni jihadist group that controls much of Iraq and Syria. There will of course be much debate and possibly a major political donnybrook in the months to come, and unexpected twists are always possible.

But what a surprise it would be if the principal legacy for Obama were not the opening to Iran, even if it were to fulfill all positive expectations, but a deepening cold war, potentially even hot war, with Russia.