Several Russia experts have speculated that Vladimir Putin's invasion of Ukraine was motivated by a desire to reassert his country's natural sphere of influence, which crumbled as the Soviet Union disintegrated in the early 1990s.

Though the Ukrainian people's courageous and surprisingly effective resistance to Moscow's aggression has exposed the limits of Russian power, Ukraine is an outlier among post-Soviet states. A large country with vast resources, Ukraine has received considerable support from the West. Smaller countries that lie within Moscow's reach would not fare nearly as well.

One prime example is Moldova. Last month, Kyiv claimed that it possessed intelligence that revealed a Russian plot to topple the government of Moldova – a country led by a pro-Western president, Maia Sandu. The aim was to replace the Sandu administration with a puppet regime loyal to the Kremlin. The Moldovan president confirmed the plot several days later, adding that it involved groups from Russia, Belarus, Montenegro, and Serbia. Sandu went so far as to prevent a group of Serbian football fans from traveling to a UEFA Europa Conference League match against Moldovan champions, Sheriff Tiraspol.

But while Moldova would struggle to fend off Russian aggression in the way that Ukraine has, it is still better insulated from Moscow's machinations than other post-Soviet states. In the South Caucasus, Armenia sits firmly in Russia's orbit. As a member of the Collective Security Treaty Organization, it is dependent on Russia as its guarantor of security. But like Ukraine, Moldova, and Georgia before it, Armenia has begun looking westward since reformist prime minister Nikol Pashinyan came to power in 2018.

The reasons for this shift are numerous, ranging from the obvious economic benefits to a desire to distance itself from Russia following last year's invasion of Ukraine. Yerevan is also concerned that Moscow is unable to adequately protect its interests following its 26-year military occupation of Nagorno-Karabakh, which ended abruptly in late 2020 when Azerbaijan retook the territory in a six-weeklong war. Although the conflict was concluded by a Russian-brokered ceasefire agreement in December of that year, the ensuing peace negotiations between Armenia and Azerbaijan have been led by the European Union.

To avoid losing its grip on the South Caucasus, the Kremlin aroused suspicion in November of last year by allegedly parachuting one of its favorite oligarchs, Armenian-born Russian banking tycoon Ruben Vardanyan, into Karabakh to serve as the political leader of the ethnic Armenian separatists that have controlled the enclave ever since the First Nagorno-Karabakh War came to an end in 1994. It appears that Vardanyan's role was to act as a spoiler in the peace process. Though he was reasonably effective in this mission, his tenure as Karabakh's de facto "prime minister" ended abruptly last month– ironically on the first anniversary of the invasion of Ukraine.

At a superficial level, Vardanyan's fall from grace might look like a success. But Russia's influence in the region is far from extinguished. As Putin has shown over the last 20 years, he tends to respond to setbacks by doubling down rather than giving up. Recent reports suggest that his next plan is to train Armenian forces so that they can strike at Azerbaijan's gas pipelines, which supply energy to Europe. If true, this would mean that Putin is looking to bypass Pashinyan and work directly with the Armenian military, which has shown a resistance to the prime minister's reformist agenda. This certainly fits with what we know about the Russian president, who has consistently used divide-and-conquer tactics as a source of leverage.

The unexpected by-product of Vardanyan's presence in Karabakh was to unite the leadership of Azerbaijan and Armenia in demanding his departure. The countries have demonstrated an interest in pursuing a peace treaty that addresses common concerns, despite being erstwhile enemies. With Vardanyan out of the picture, having been officially sacked from his role as head of the Armenian leadership in the province, peace negotiations are once again a possibility and Vardanyan is no longer a barrier to progress. Nevertheless, Russia is certain to meddle again.

But it's not just Armenia that needs to worry about Kremlin interference. Yerevan may be far more dependent on Moscow than Baku is, but Azerbaijan is also vulnerable to Putin's malign influence. Russian peacekeepers have been stationed in Karabakh since the end of 2020, as per the terms of the ceasefire agreement that brought the Second Nagorno-Karabakh War to a close. But a ceasefire is not peace and, with Russia distracted by events in Ukraine, Putin would certainly prefer to keep the conflict frozen than resolved, if only to keep open the option of heating it back up again.

Armenia and Azerbaijan appear to have reached a unique crossroads in recognizing that their interests are better served by working together to find a common path forward than stewing in decades-long animosity. But to achieve this, they require help in keeping Moscow at bay. European powers must do everything they can to support the nations in their efforts to bring peace to the South Caucasus.

There are many potential zones for collaboration between Armenia and Azerbaijan – transport, energy, border delimitation, and mutual recognition of one another's sovereignty. A peace treaty could help facilitate cooperation in these areas. But both countries need to seize the window of opportunity before it's too late. History reveals that less powerful countries have been squeezed by dominant powers when their cooperation is perceived to be a threat to continued interference.

Vardanyan's exit creates an unusual opening for Armenia and Azerbaijan to build a historic peace arrangement. The time has come to seize the moment.

Prof. Ivan Sascha Sheehan is the associate dean of the College of Public Affairs and past executive director of the School of Public and International Affairs at the University of Baltimore. Opinions expressed are his own.