Tension is mounting along the Pakistan-Iran border in the volatile Baluchistan province after an anti-Shiite militant group kidnapped at least 14 Iranian Revolutionary Guards last week.

Iran has warned that if Pakistan does not “confront” the Sunni militants involved in cross-border attacks, Tehran will hit at bases inside the country.

The Guards were abducted from the border post at Mirjaveh in Sistan-Baluchistan province and taken to the Pakistan side of the border. The arid region in southwestern Asia consists of the Pakistani province of Baluchistan, the Iranian province of Sistan and Baluchistan, and the southern areas of Afghanistan.

Baluchistan authorities are still clueless about the whereabouts of the kidnappers. A joint search operation jointly led by the director generals of military operations of Iran and Pakistan did not succeed in tracking down the hostages.

“No concrete development has so far been made by the law enforcing agencies as we are still in the dark about the identity and location of the suspects,” Muhammad Naeem Bazai, the Director General of the Baluchistan Information Ministry, told Asia Times.

However, official sources in Baluchistan confirmed that the military intelligence personnel of Pakistan and Iran were working to ascertain the whereabouts of the Iranian guards in coordination with the joint search operation.

Brigadier General Mohammad Pakpour, the head of the Iranian ground forces, was quoted by the Iranian official news agency as saying that Iran was ready to conduct “joint military operations with Pakistan” against the militant groups to release the kidnapped personnel. Iranian authorities claimed Saudi Arabia was funding separatist groups on its territory through ‘some regional powers,’ a claim Riyadh persistently denied.

The incident strained relations between Pakistan and Iran and Iranian authorities summoned the Pakistani envoy in Tehran and lodged a strong protest over recurring terror attacks on Iranian security forces from across the border.

Amid increasing militant activities in the border area, Iran’s Foreign Minister Javed Zarif contacted his Pakistan counterpart Shah Mehmood Qureshi on Wednesday and sought Pakistan’s cooperation returning the security officials taken hostage.

Iran had officially held Jaish al-Adl responsible for the killing of border forces and claimed the long-range guns used in the incident were “fired from inside Pakistan.” The situation escalated when the head of the Iranian armed forces warned Islamabad that Tehran would hit bases inside Pakistan if the government did not confront the militants.

Jaish al-Adl, which later claimed responsibility for kidnapping the Iranian guards, is a Salafi extremist group fighting for the liberation of Sistan-Baluchistan province of Iran where Sunni Muslims despite being in majority are allegedly persecuted by Iranian border forces.

Jaish al-Adl is believed to have been infuriated by the Iranian Government’s active support in Syria against Islamic State, which they saw as an attack on Sunni Muslims.

A highly-placed source in Baluchistan’s capital city Quetta said: “The Iranian side came down on Pakistan like a ton of bricks, calling for the elimination of militants’ dens and a halt to infiltration by Jaish al-Adl (Army of Justice) operatives in Iranian territories,” the source revealed, adding that the Iranian side was angry about persistent attacks on the Iranian Revolutionary Guards from the Pakistan side.

The Pakistani security forces, he said, knew of the hideouts of the terrorists because the security agencies supplied them with food, arms and ammunition.

“All our neighbors – Afghanistan, China, India and Iran – have accused us of harboring hardcore militants and terrorists who cross over to their countries, commit subversive activities and go back to their safe havens in Pakistan,” the source said.

He added that the border stand-off with Afghanistan, India and Iran was a serious drain on the public purse as the economy was already in bad shape.

Attacks on Iranian forces

A number of Jaish al-Adl members had taken shelter in Pakistan’s Baluchistan province to carry out operations against Iranian security forces. The group claimed to have carried out a series of operations against Iran’s security forces and Revolutionary Guards in Sistan and Baluchistan province.

The operation included hitting Revolutionary Guards’ vehicles and convoys, kidnapping Iranian border guards and orchestrating attacks on the military bases inside Iranian territory. The group claims to have killed dozens of Revolutionary Guards in their operations.

Last year the group targeted and killed at least 10 border security guards on the Pakistan-Iran border. To put pressure on Pakistan to take action against the militants, Iran’s Foreign Minister Mohammad Javad Zarif visited Pakistan and had meetings with the country’s top brass in an effort to improve border security. Although Pakistan committed to deploying additional troops along its border, the situation has deteriorated.

In 2014, Iranian forces came onto Pakistan territory to storm the hideouts of the Sunni terror group following the kidnapping of five security personnel. Iran also fired mortar shells at a small Pakistani border town to register its growing anger at Islamabad’s failure to curb terrorist attacks in its restive Sistan Baluchistan province.