Although it is easy to sympathize with the Iranians, it is not in the U.S. interest to get involved in the conflict.
Iran has oil, they sit on one side of the Straits of Hormuz, they share a border with Afghanistan, and they have nuclear technology. If they do not already have the capacity to manufacture nuclear weapons they will in the very near future.
Iran is not a country the world can afford to ignore indefinitely. U.S interest, international interest, is for stable and largely peaceful government in Iran. Democracy is preferred but not mandatory.
A destabilized Iran is a danger to everyone. Other nations can look away only so long before this becomes a matter of international concern.
That backing the protesters means standing up for our own political ideals and heritage is a pleasant bonus. Sometimes you get lucky that way.
Practically speaking, the youth have little chance if they turn to violence, even with our support. The moment we offer aid, Khamenei will declare proof of American interference and brand the protesters as collaborators of western imperialists, then call in the revolutionary guard. The revolutionary guard is political army designed to deal with this sort of situation and are loyal to the current regime. Counterinsurgency is a very different game when you are content to use wide-scale slaughter and intimidation to win. In the end, it is likely that the current regime will stay in power and have a serious bone to pick with us. Furthermore, it would be yet more ammunition for the radicals who claim we are evil imperialists out to destroy the Muslim world.
Read the news. Khamenei is already hurling those accusations, is already calling out the Revolutionary Guard and the Basij militias. He's already shot that bolt.
Yes, if we arm the insurgents they might lose, and we might be faced with a hostile Iran. If we do nothing the insurgents might lose and we might be faced with a slightly less hostile Iran.
Or we arm the insurgents, they win, and we have a friendly Iran.
It is a risk, but if the violence is increasing, the risk is small and growing smaller, while the reward large and getting larger.
The time to gamble may very well be now.
Ultimately, it is not the role of the U.S. to use weapons to promote democracy in the world. We have ignored hundreds of other instances of the people being attacked by there governments, and there is no reason to get involved this time either.
True enough. We have no interest in "promoting democracy." We do have interest in promoting stable government in strategically situated nations with nuclear ambitions