War in West Asia: How Iran-Azerbaijan ties moved from managed hostility to the brink of cross-border engagement

Two Azerbaijans

Modern interaction between Iran and Azerbaijan, home to two of the world’s largest Shia populations, is characterised by a root difference between them. While Iran transformed into a Shia theocracy following the 1979 Islamic Revolution, Azerbaijan adopted a strict secularism in 1991 after the dissolution of the erstwhile Soviet Union — which Iran viewed as a Western-oriented governance model.

Divided along the Aras river — both a natural and a modern-day geopolitical boundary — since the 1828 Treaty of Turkmenchay, the Azeris (as the people of Azerbaijan are called) have been historically sandwiched between Russian and Persian culture. Close to 15 million Azeris live in north-western Iran, overshadowing Azerbaijan’s own population of roughly 10.5 million. Since Azeris on both sides of the border belong to the same ethnic Turkic group, Tehran perceives the threat of secession as a real possibility.

In their efforts to suppress Azeri separatist thought, Iran has never shied away from extreme measures. During the 2011 protests over the drying of Lake Urmia, Iranian security forces arrested dozens of peaceful Azeri demonstrators in Tabriz, the capital city of Iran’s border East Azerbaijan province. Last year, the Tabriz Islamic Revolutionary Court issued heavy prison sentences to over a dozen Azeri activists advocating for ethnic minority and environmental rights, charging them with “conspiracy against the state”.

Meanwhile, Iran’s consistent support of Armenia (which is dominantly Christian) in its conflicts with Azerbaijan can be traced to the first war they fought over the disputed territory of Nagorno-Karabakh (1988-94). Iran had supplied Armenia with critical economic, energy, and transit lifelines as a strategic counter, banking on the scenario that a weakened Azerbaijan would quell the possibility of ethnonationalist uprisings among Iran’s own Azeri population

The Israel-Azerbaijan-Turkey axis

What explains Iran’s foreign policy in West Asia is that it is geographically encircled by regional players Tehran has had historically complex ties with.

Azerbaijan’s supply of crude oil to Israel (accounting for 46.4% of Israeli oil imports last year) in return for advanced defence technology is a red flag for Tehran. The 2021 “Conquerors of Khaybar” military drills along the Aras River saw Iran’s Islamic Revolutionary Guard Corps publicly state the manoeuvres were necessary to combat the “presence of the Zionist regime”. Iran has also accused Baku of cooperating with the Israeli intelligence agency Mossad for the use of Azerbaijani airbases.

Iranian anxieties are further compounded by Azerbaijan’s guiding philosophy of “One Nation, Two States”, coined by former president Heydar Aliyev. It asserts that while Turkey and Azerbaijan are sovereign entities, they share an inseparable ethnic and cultural destiny. This was formalised by way of the 2021 Shusha Declaration, a mutual defence pact that legally obligates Turkey (a NATO member) to defend Azerbaijan, ensuring any Iranian strike risks escalating a wider conflict.

‘Trump Route’

Moreover, the balance of power in the region has shifted following the Armenia-Azerbaijan peace agreement was signed in August 2025 at a White House summit mediated by US President Donald Trump. Although a final treaty is yet to be signed, the summit resulted in a “Trilateral Joint Declaration”, which includes the creation of a 43-km transit corridor connecting mainland Azerbaijan to Nakhchivan through southern Armenia. Officially called the Zangezur corridor, the project was dubbed the “Trump Route for International Peace and Prosperity”.

Crucially, the agreement granted a US-led consortium exclusive development and management rights over the corridor for 99 years. While Armenia retains sovereignty over the land, the agreement physically severs Iran’s direct border with Armenia — validating Tehran’s deep geopolitical paranoia.

The late Iranian Supreme Leader, Ayatollah Ali Khamenei, had publicly enshrined border preservation as a strict foreign policy doctrine. In 2022, he told Turkish President Recep Tayyip Erdogan that “if there is a policy intended to block the Iran-Armenia border, the Islamic Republic will oppose it”.

It is this complicated history that seems to have played out in the events following last week’s strikes on Nakhchivan, which also signalled a possible shift from managed hostility to direct cross-border engagement.