Russia knows that soft power requires hard power. Given the mutually hurting stalemate in Syria, the only way to convince Assad that the terms of peace will not be against his interests was to back him up militarily. 

As nationalism may seduce the masses, so may vanity have the same effect upon individual diplomats engaged in conflict resolution. While some may debate what strategic interests, conspiracies or prejudices are at play in motivating policy, too frequently it may be the egos of the personalities involved. 

Rosy Senanayake and Kumar Sangakkara are two extremely popular Sri Lankans and shadows that have befallen their careers have caused heartburn among their fans. [...] This brings in the key question: Can anyone who is not a professional diplomat and wants to be one or is selected as one be a successful diplomat?

If Congress rejects the deal, we will project globally an America that is internally divided, unreliable, and dismissive of the views of those with whom we built Iran’s sanctions architecture in the first place. I and other American diplomats around the world draw every day on our nation’s soft power, which greatly enhances our ability to mobilize other countries to our side.

Iran's approach to foreign policy changed dramatically after Hassan Rouhani was elected President of Iran in 2013. The most serious and comprehensive negotiations regarding Iran’s nuclear program started in 2013 between Iran and six world powers including the United States. An interim agreement was reached on November 24, 2013. A framework agreement was reached on April 2, 2015. And finally, the comprehensive deal was reached on July 14, 2015 to ensure that Iran’s potential pathway to developing a nuclear weapon is blocked.