

Pakistani Rangers patrol along the Pakistan-India border area of Wagah on October 16, 2014. But this isn't the only frontier Islamabad has to worry about. AFP PHOTO/ Arif ALIArif Ali/AFP/Getty Images

We're accustomed to reports of U.S. drone strikes in Pakistan. So too the almost routine exchanges of fire between Indian and Pakistani soldiers stationed across one of the world's militarized borders, where skirmishes have led to more than a dozen deaths this past month.

But hostilities have flared this week along a more forgotten frontier: Pakistan's long desert border with Iran.

In recent days, Tehran and Islamabad have summoned each others' envoys after reports of gunfights and incursions. On Oct. 17, Pakistani officials claimed that 30 Iranian guards in six vehicles started shooting at a vehicle carrying members of the Pakistani Frontier Corps, two miles inside Pakistan's border. One soldier was killed and three others were wounded.

The alleged incident, which Tehran has not directly addressed, followed an angry warning on Thursday from the second-in-command of Iran's influential Revolutionary Guards after four of its soldiers were killed by unknown assailants at a post in Iran's eastern Sistan and Baluchestan province, which abuts Pakistani Baluchistan. The Iranians believed the attackers were operating from Pakistani territory. "We are, in principle, against intervening in the affairs of any country," said Brig. Gen. Hossein Salami, "but if they fail to abide by their obligations we will have [no choice but] to act."

Pakistani officials dismissed Iran's allegations, with language similar to what Islamabad often trots out when accused by neighboring India of tacitly supporting terrorism there. "If Iran has evidence that elements from Pakistan are involved in activities against Iran, they should share it with us,” said a Pakistani foreign ministry spokesman on Friday. "Our information is that these incidents took place inside Iranian territory by Iranians and that is corroborated by their own accounts. It is not helpful to externalize problems."

Pakistan's Baluchistan province, where Iranian officials believe anti-Iran Sunni militant groups operate, is vast and rugged and comprises some 40 percent of Pakistan's landmass but only 5 percent of its population. A separatist, ethnic Baluch insurgency blows hot and cold there. Extremist Sunni militias have been behind a spate of grisly sectarian attacks on Pakistani Shiites, including many pilgrims bound for holy sites in Iran, which is a predominantly Shiite country.

Iranian officials have in the past pointed the finger at al-Qaeda-linked group Jundullah, which is responsible for suicide bomb attacks and raids on Iranian soil that Tehran links to Pakistan. The fighters, though, say they are resisting Iranian oppression of Sunni Baluch on its side of the border.

Pakistani news reports this week cited the activity of another militant group, Jaish al-Adl, a Salafist organization which has already targeted Iran this year, including abducting five Iranian border guards in February. Four were released, but one was killed.

Meanwhile, hostile Iranian actions have led to Pakistani civilian deaths. Rockets fired by Iranian guards have killed about a dozen Pakistani civilians in the border region over the past decade, reports the Karachi-based Dawn newspaper.

The current round of border tensions take place over a wider and even more fraught geopolitical landscape. The historic region of Baluchistan was the arid wasteland through which Alexander the Great's armies left India more than 2,000 years ago. But beneath its soil are largely untapped oil and natural gas reserves.

A massive Chinese-financed port at Gwadar, on the Pakistani side, is being matched by a similar Iranian development at Chabahar, which has attracted a considerable amount of investment and interest from India. Both spots may become linchpins for trade and other strategic interests in the region, and their emergence has been cast by some as a sign of India and China's growing rivalry in Asia.