No country stands to lose more from the collapse of the Assad regime in Syria than its lone regional ally, the Islamic Republic of Iran. For this reason, no country has offered more financial and strategic aid to try and keep afloat a drowning Bashar Assad than Tehran.

The Iran-Syria alliance is a not a natural bond between nations, but a tactical-cum-strategic alliance between two authoritarian regimes. Mutual contempt for Saddam Hussein’s Iraq brought them together in 1980, and mutual fear and loathing (in that order) of the United States and Israel has helped sustain them.

Iran’s interests are to ensure that Syria remains a geo-political ally and a thoroughfare to Hezbollah. Given their lack of confidence that a Sunni-ruled, post-Assad order in Damascus would guarantee these interests, they’ve doubled and tripled down on Assad, even as civilian casualties in Syria approach 20,000. In this context, international diplomatic efforts by Kofi Annan or others to compel Tehran to abandon Assad are all but futile.

In the words of Iranian envoy Saeed Jalili, who met Bashar Assad Tuesday in Damascus, “Iran will absolutely not allow the axis of resistance, of which it considers Syria to be a main pillar, to be broken in any way." In other words, if the ends are opposing the United States and Israel, almost any means can be justified.

Iran’s combination of agility and chutzpah, however, should not be underestimated. When the Assad regime finally loses Damascus, Tehran will likely try and take credit for his exit, and use their petro-dollars to cultivate and co-opt his successors, much like they did in Iraq after the fall of Saddam Hussein.

What’s important to Tehran is not the sectarian identity of the men who run Damascus, but their ideological outlook. Can they be partners in resistance?

In contrast to Iraq, however, where their Shiite brethren were a demographic majority, Iran will be working with an increasingly sectarian Sunni population whom they’ve been indirectly complicit in massacring the last two years.

Consequently, until then, Tehran will continue to advocate and pursue two objectives—Assad staying and calm restored—that are irreconcilable and bloody.

This article was originally published in the New York Times.