Iran controls over 70,000 Iranians and non-Iranian minions in Syria and has over 250,000 fighters and operatives on its payroll. Its army includes about 10,000 Revolutionary guards, around 6,000 regular Iranian army, around 10,000 Hezbollah fighters from Lebanon and the rest are from Iraq, Afghanistan, Pakistan, Palestinians and others.
Iran has spent approximately $100 billion on the Syrian war. The sanctions relief given to Iran as a result of Obama's "nuclear agreement" has given Iran a slush fund to invest $35 billion of our tax dollars in Syria on weapons and training and building a Command Center to control terror operations and weapons flow.
As a result of this slush fund, Hezbollah now has an estimated 155,000 rockets and missiles in Lebanon directed at Israel. One in four homes in southern Lebanon is a Hezbollah home with rocket launching room.
Iran has divided Syria into five sections and has over 13 military bases. Their command center is located near the Damascus airport because they believe the airport is the last to fall.
Iran wants to establish hegemony in the Middle East, and the Saudis, Egyptians and Jordanians know it. Their fear and concern about Iran is what drove them to work with Israel and America to stop Iran. Iran's role and work in Syria has led to ISIS and the refugee crisis across the middle east, Europe and the rest of the world.