Northern Iraq's Kurdistan Region maintains a complex relationship with Tehran that balances economic dependence with ethnic solidarity toward Iranian Kurds across the border. Analysts assess that Iranian instability could trigger a mass influx of Kurdish refugees into the KRI while simultaneously emboldening Kurdish separatist groups like PJAK to establish operational bases with reduced fear of Iranian cross-border strikes. The Kurdistan Regional Government would face a dilemma: supporting Kurdish aspirations risks provoking Turkey, which views any Kurdish autonomy expansion as a threat, while aligning with Tehran's successor regime could alienate its own population. Meanwhile, Iranian-backed Shia militias embedded in Iraq's Popular Mobilization Forces could lose coordination and funding, potentially fragmenting into competing factions fighting over territory and smuggling routes in disputed areas like Kirkuk and Diyala provinces.

Azerbaijan shares a border with Iran's Azeri-majority provinces, where an estimated 15-20 million ethnic Azeris represent Iran's largest minority group. Analysts suggest that any fracturing of Iranian central authority could ignite pan-Azeri sentiment on both sides of the border, presenting Baku with a temptation to support co-ethnic populations while risking direct confrontation with whatever power holds Tehran. President Aliyev's government, emboldened by its 2020 victory in Nagorno-Karabakh and backed by Turkish military cooperation, could see Iranian instability as an opportunity to expand influence southward. However, Russia — which maintains a peacekeeping presence in the region and views the South Caucasus as its sphere — would likely oppose any Azerbaijani territorial ambitions. The Baku-Tbilisi-Ceyhan oil pipeline and the Southern Gas Corridor, both critical European energy routes, run through this volatile geography, meaning any escalation carries global energy market implications.

Iran's 572-mile border with Afghanistan is already one of the most volatile in the region, with drug trafficking, water disputes over the Helmand River, and periodic armed clashes between Iranian border guards and Taliban forces. Analysts assess that Iranian instability would remove the one power that has maintained a functioning security presence on the western Afghan frontier, potentially creating an ungoverned corridor stretching from Herat province to Iran's Sistan-Baluchestan. The Taliban government, already struggling to control its own territory, would face pressure from smuggling networks exploiting the vacuum while millions of Afghan refugees currently inside Iran could be forced back across the border into a country with no capacity to absorb them. Iran has historically maintained influence over Afghan Shia Hazara communities and funded Fatemiyoun Brigade fighters — the collapse of that patronage network could leave armed, combat-experienced men without a sponsor, creating a free-agent militia problem in an already fractured region.