Iran and Pakistan were on the brink of a full-blown conflict after they exchanged deadly cross-border attacks in January.
The unprecedented flare-up reignited a long-running dispute between the neighbors over cross-border militancy. For decades, the countries have accused each other of harboring armed groups that carry out attacks on the other.
Now, Iran and nuclear-armed Pakistan appear to be expanding their cooperation as they attempt to curb the rising number of attacks carried out by Baluch separatists and militant groups operating along their shared 900-kilomter-long border.
"The two sides have turned a corner in their relationship," said Farzan Sabet, a senior research associate at the Geneva Graduate Institute.
In July, Islamabad handed over to Iran an alleged member of Jaish al-Adl, a Baluch separatist militant group that is believed to be operating out of Pakistan. In return, Iran transferred a Pakistani Baluch separatist figure to Islamabad.
In early November, Jaish al-Adl claimed that 12 of its fighters were killed in a joint operation by Iran and Pakistan. Tehran praised the assault but said that it was conducted by Pakistani forces alone.
Source Of Instability
Iran's southeastern province of Sistan-Baluchistan and Pakistan's southwestern Balochistan Province have been the scene of decades-long insurgencies.
The vast and impoverished provinces are home to the Baluch, an ethnic minority in Iran and Pakistan. Baluch in both countries have long faced discrimination and violence at the hands of the authorities, which they accuse of exploiting the region’s natural resources.
Residents stand beside a charred vehicle near a collapsed railway bridge the morning after a blast caused by separatist militants in Kolpur in the Bolan district of Balochistan Province in August.
Jaish al-Adl and the Baloch Liberation Army (BLA), the largest Baluch armed group in Pakistan, have become increasingly potent fighting forces in recent years.
The groups have adopted more lethal tactics, including suicide bombings, and expanded their recruitment. They have also exploited growing local anger at Tehran and Islamabad, and acquired more sophisticated weapons.
SEE ALSO: The Rise Of The Baloch Liberation Army In PakistanThe BLA on November 9 claimed responsibility for a suicide bombing targeting soldiers at a train station in Balochistan that killed at least 26 people.
On October 26, Jaish al-Adl attacked a police patrol in Iran's Sistan-Baluchistan Province, killing 10 officers.
Aziz Baloch, an independent Pakistani security expert, says Tehran and Islamabad are coordinating and cooperating on "security and border management for the first time."
Baluch armed groups "have become a leading source of internal instability" in both countries, said Baloch, adding that Iran and Pakistan "have grasped that without turning this situation around through cooperation, they will suffer mounting losses."
Imtiaz Baloch, an analyst covering Balochistan for Khorasan Diary, a website tracking militant groups in Afghanistan and Pakistan, says the collaboration between Iran and Pakistan is deeper than publicly acknowledged.
"Cooperation between the two is deepening and gathering pace," he said.
Economic Incentives
Experts say Pakistan and Iran -- who are both dealing with economic crises -- also have financial incentives for expanding cooperation and tackling cross-border militancy.
Pakistani air strikes hit Iran's Sistan-Baluchistan Province near the two countries' border in January.
Pakistan’s Balochistan is a resource-rich province that is home to dozens of multibillion-dollar Chinese-funded development projects.
Militants have killed at least seven Chinese workers in Pakistan this year, threatening to derail the $60 billion China-Pakistan Economic Corridor.
Meanwhile, Beijing is a top importer of Iranian oil and a leading investor in its freefalling economy. The Chabahar Port in Sistan-Baluchistan is a key hub for imports and exports to neighboring Afghanistan.
Sabet of the Geneva Graduate Institute said the security risks emanating from Baluch areas in Iran and Pakistan and their geo-economic importance have magnified their place in the development plans of both countries.
"This has led the two governments to embark on an effort to suppress the violence there," he said.