Iran and Pakistan are currently entangled in a dispute marked by artillery exchanges and the suspension of diplomatic relations. After a brief period of military and verbal escalation, it is highly probable that both countries will seek ways to avert a major confrontation, which neither can afford.
The root cause of the artillery exchanges lies in mutual accusations: Iran claims that Pakistan is harboring anti-Iranian Baluch “terrorists,” while Pakistan accuses Iran of sheltering anti-Pakistani Baluch “terrorists.”
Baluchistan, a region on the Arabian Sea shared by Iran, Afghanistan, and Pakistan, is home to various independence-seeking guerrilla groups. Similar to the Kurdish situation, neighboring countries often support these groups to destabilize their local rivals, reminiscent of the 1980-1988 Iran-Iraq war when Iraqi Kurds were backed by Iran and Iranian Kurds by Iraq. Nothing new under the sun, then. Notably, the current situation between Iran and Pakistan mirrors historical instances where creating problems for neighbors, even without outright warfare, is considered a profitable exercise. This is particularly true for Iran and Pakistan, both with established records in fostering, organizing and sending abroad terrorist groups.
Addressing the question of “why now?,” speculations abound. The theory suggesting that Iran is warning Pakistan to distance itself from the United States is apparently appealing, but not very substantiated. Not only because Pakistan has perhaps stronger ties with China than with the United States, but also because the rulers in Tehran should know that determining a singular authority in Pakistan is challenging, considering the complex interplay among the government, military (which practically equates to the government presently), intelligence agencies, influential opposition parties, feudal families, regional interests, and terrorist groups at large. Deciphering who holds sway over what in Pakistan is always a formidable challenge. Let us not forget that Pakistan created the Taliban to take over Afghanistan, but then fought against the Taliban after 9/11, despite continuing to host their leadership and even sheltering Osama bin Laden on its territory.
Rather than relying on speculation, it is more prudent to focus on the certainties. The argument that relations between Pakistan and Iran were excellent until the Jan. 17 attack is flawed by the habit of always wanting to box things into sharp, well-defined categories: either friend or foe, either black or white. While both Iran and Pakistan share some common interests and a powerful friend in China, they also harbor numerous reasons for rivalry.
First of all, it makes little sense to assert that the Islamic Republic of Iran and the Islamic Republic of Pakistan share faith and institutions because of their shared label. Iran is Shiite-majority and Pakistan Sunni-majority; after the 1979 revolution, political roles in Iran have been exclusive to Shiites, and in Pakistan only a few Shiites have occupied minor roles, apart from the first president, Iskander Mirza, who held a role with minimal political influence. The disparity in their interpretation of Islam and Sharia is not solely rooted in the Shiite-Sunni divide but is driven by political considerations rather than adherence to religious commandments.
Deeper motivations for their rivalry lie in their perspectives on Afghanistan and, above all, their relationships with India. Iran views Afghanistan as a provisionally separate eastern province (the same language is mostly spoken there as in Iran), whereas for Pakistan, which envisions itself as the legitimate heir to the Muslim Mughal Empire, it is a provisionally separate western province (Kabul was part of the Mughal empire, indeed it was the first capital of the dynasty). Pakistani intellectual Tariq Ali wrote that “the Taliban takeover in Kabul  had been the Pakistan army’s only victory. Privately, the ruling elite – officers, bureaucrats and politicians – congratulated each other for having gained a new province. It almost made up for the 1971 defection of Bangladesh.” For this reason, Tehran bitterly opposed the Taliban regime, prompting Iran’s active involvement in the 2001 war aimed at ousting them from power.
The relationship with India is much more delicate, especially, obviously, for Pakistan. There is no doubt that the ties between New Delhi and Tehran are stronger compared to those between Islamabad and Tehran (and for that matter, the relations between Islamabad and Beijing are more robust than those between Beijing and Tehran). Pakistan's strategic approach towards Afghanistan has consistently aimed at avoiding being ensnared by adversaries. Any improvement in relations between Iran and Afghanistan is perceived by Islamabad as a potential threat. Currently, tensions between Pakistan and the Taliban, who have been in control of Kabul since 2021, have reached unprecedented levels, leading to military clashes along the border. In contrast, relations between Tehran and Kabul have never been so good – in a context, it goes without saying, where the notion of “goodness” is an extremely relative and fluid concept.
Even more concretely: China has decided several years ago to build its main strategic port in the Indian Ocean in Gwadar, Pakistan, which should serve as the terminus for one of the most crucial corridors of the Belt and Road Initiative. Responding to this move, India, China's systemic rival, initiated the development of a substantial port in Chabahar, located approximately 160 kilometers in a straight line from Gwadar, but situated in Iran. While the Indian project may not currently compete with the scale of the Chinese undertaking, but in the future, who knows. What is known now is that Gwadar and Chabahar are both located… in Baluchistan.