Russia will lose an ally if Iran falls. Why does it matter for Moscow?

As Iran’s future hangs in the balance as civil unrest gathers steam, its powerful ally Russia can do little but watch and wait as the U.S. ponders its next move against the Islamic Republic.

U.S. President Donald Trump has not ruled out using military strikes against the conservative religious regime that has ruled Iran since 1979. On Tuesday, he repeated that threat, warning the U.S. would take “very strong action” if Iran executed arrested protestors. Trump has already said any country doing business with Iran would be hit with a 25% tariff.

Russia will be focused on how events unfold in Iran given Tehran’s position as a key strategic, military, economic and trade partner for Moscow in the Middle East.

The prospect of another ally falling in the Middle East will be a worrying one for Moscow, particularly after it has seen its alliances with Venezuela, Syria, and the Caucasus upended recently, denting its power and influence abroad.

“Moscow sees the potential loss of Iran as a much more significant risk to both its regional national posture than it saw the loss of Syria, Venezuela, or arguably its influence in Armenia over the last few years,” Max Hess, founder of political risk consultancy Enmetena Advisory, told CNBC Tuesday.

“The reason for this is because Iran is itself a regional power projector, which offers Russia a platform to build alliances and expand its own influence,” he said.

Mario Bikarski, senior analyst of Europe and Central Asia at Verisk Maplecroft, agreed that any regime collapse would be worrying for Moscow as it would represent another loss of power and influence, but could also unleash wider regional instability in the Caucasus region that separates Russia and Iran.

“There have been Iranian protests in the past, and Russia has always looked at them but never reacted, because they probably hoped that the Iranian regime will be able to withstand the pressure. But [this time] the pressure has been building up, and it’s not only domestic, it’s also external,” he told CNBC Tuesday.

“Should the Iranian regime fall, Russia would probably have to scramble and find new ways to ensure that instability does not reach its borders, and also that it’s maintaining some influence in the region,” he said.

If a leadership vacuum emerged in Iran and rival factions vied for power, leading to further violence and unrest, that would mean “big security trouble for Russia and for a lot of other countries in the region,” Bikarski warned.