Iran has paid a heavy price for its military intervention in Syria since 2014. The Revolutionary Guards and Quds Force, along with Lebanon's Hezbollah and Shiite militias from Iraq, Afghanistan, and Pakistan have suffered thousands of casualties. Iran has invested billions of dollars in propping up the regime of Syrian President Bashar Assad and the war Assad is waging against his enemies. That had ramifications back in Iran: In recent months, thousands have been marching in anti-regime protests sparked by economic distress, calling for "Death to Syria" and "Death to Palestine." The protesters are calling on the Iranian government to stop funding Assad and Hamas and to spend the money on the welfare of the Iranian people. This means bringing the country's forces home.
Now Iran will have to pay. The Assad regime is stabilized and the governments that have fingers in the Syrian pie are examining their options. Given that, Iran wants to be the main foreign power broker, for a number of reasons: Syria has been the Iranian regime's only ally since it came to power; Syria is an important base from which Iran can expand its influence in Iraq and Lebanon – both of which have dominant Shiite populations. No less importantly, Iran sees Syria and Lebanon as its front line against Israel.
To solidify its standing, Iran is seeking to strengthen its security ties with Syria. The most important component of that is to install military forces there for the long term to ensure the stability of the Assad regime, maintain its influence, and up the threat it presents to Israel. At the same time, Iran is working toward closer economic ties with Syria – to recoup some of the massive costs incurred by its military intervention there, among other reasons. Aside from that, Iran is also forming ties with various actors in Syria, such as building Shiite militias for the eventuality that the Assad regime collapses.
But these efforts are turning out to be failures. Since 2015, Russia has also been a player and has been providing Assad with important military aid. Syria placed an air force base and a naval base at Russia's disposal for dozens of years. Russia gradually usurped Iran's place as the leading influencer that will determine Syria's future and took advantage of its status to expand its own economic and military ties, over Iran's objection and at the expense of Iran's ties to the Assad regime.
Even Iran's plan to keep its forces in Syria for the long term has encountered difficulties. Israel, with U.S. support, is consistently attacking Iranian-Shiite military targets where Iranian forces are exposed, and Iran has no viable response. Russia might have made it clear that it cannot remove the Iranian military presence from Syria, but it is willing to take action to ensure that the Iranians stay at least 85 kilometers (53 miles) from the Israeli border. Despite cooperating with Iran in the Syrian war, Russia is not helping it when it comes to the Israeli strikes and is giving the Israeli Air Force considerable latitude.
The situation is further complicated by the defense agreement that Iran recently signed with Syria, which among other things deals with Iranian aid to help the Syrian military and military industry get back on its feet. The deal sends a message to Russia that Iran's military ties with Syria are still strongly anchored. The deal might just be cover for a long-term deployment of Iranian forces in Syria, under the guise of "advisers."
Iran's troubles will get worse when an end to the Syrian war is declared, which could include a demand that all foreign forces in Syria withdraw, including the Iranian military and Shiite militias. The U.S., and apparently Turkey, will support that demand. Russia might, too, because it understands that if Iranian forces remain on the ground, it will lead to perpetual clashes between Iran and Israel that will destabilize the situation in Syria. In that case, not even a defense deal will be able to help Syria.
