How to react to Iran's new smiley-faced president, Hassan Rouhani? 

Smile back, but don't stop squeezing Iran with sanctions. 

Rouhani has offered a series of positive gestures since taking office in early August. He has released some political prisoners. He sent New Year's greetings to Jews in Iran and around the world. He took a phone call from the president of the United States. 

Does any of this portend real change in Iran? 

The case for skepticism is strong. None of the regime has changed in any way. Iran continues to make mischief through the region, most horrifically by supporting the brutal actions of the Bashar al-Assad regime in Syria. As far as anyone can tell, Iran pursues nuclear weapons as determinedly as ever. 

Rouhani himself is no liberal and no Democrat. An early supporter of the Ayatollah Khomeini, Rouhani held senior positions in the Iranian state during the regime's most vicious period of international terrorism, the early 1990s - the years in which Iranian-backed terrorists carried out assassinations in Berlin and Paris and carried out two terrible bombings of Jewish targets in Buenos Aires, killing 114 people and wounding nearly a thousand more. 

As Iran's chief nuclear negotiator in the 2000s, Rouhani nimbly evaded international efforts to achieve a peaceful end to the country's drive for weapons of mass death. 

More fundamentally, the president of Iran does not govern the country's national security system. The military and the secret police answer to the supreme leader, the Ayatollah Khameini, who has very emphatic geopolitical ideas of his own. Compared with all that, a cheerful tweet and a few words of condemnation of Nazi crimes don't seem much of an offset. 
Does he direct the military as well?
military