To that end, to enforce the deal, the US must focus not only on preventing Iran from getting nuclear weapons, but how to force it to change its behavior, which was and still is the real cause that instigated international clamor against Tehran's nuclear program.
First, now that there are open channels between the US and Iran, Washington should make it abundantly clear (behind the scenes) that Iran must cease and desist its belligerent conduct, and the US will not hesitate to undertake painful punitive actions to stop it, irrespective of the deal.
Second, notwithstanding the personal disdain between President Obama and Prime Minister Netanyahu, both will have to swallow their pride and mend their relations. This deal, however flawed, is better for Israel than no deal. Standing together will send a clear message to Tehran that nothing can compromise America's commitment to Israel's national security. This would significantly help sway some members of Congress from opposing to supporting the deal.
Third, the President should dramatically enhance the security of the Gulf States by offering the weapons and training necessary to warn Iran that the US will have zero tolerance to any meddling in the affairs of its allies in the Gulf. The US should also consider offering a formal defense treaty, which could certainly prevent proliferation of nuclear weapons, as Saudi Arabia and Egypt have already indicated they might pursue them in the wake of the deal.
Fourth, regardless of how eager President Obama is to sustain the deal, under no circumstances should the US permit Iran to commit any infraction connected to the deal with impunity. This will dramatically enhance the prospect that Iran fully adheres to every nuance of the deal or face terrible consequences.
Fifth, the President should take advantage of the common concerns that the Sunni Arab states and Israel share about Iran's threat. The US should facilitate the development of a strategic plan between the two sides, some of which is already taking place, to blunt any Iranian effort to bully its neighbors.
Although President Obama views the Iran deal as his signature foreign policy achievement, he will not see it come to fruition while still in office. He will leave behind this unfinished business to his successor, and his legacy will hang in the balance for years to come before historians render their final judgment.