Two lesser-known militant groups on the Pakistani-Iranian border are at the heart of a diplomatic crisis between the two countries following tit-for-tat air strikes on each other's territory.
On Tuesday, Iran struck targets inside Pakistan, in the border province of Balochistan.
Tehran said it had hit bases belonging to the Sunni militant group Jaish Al Adl, which it blames for a series of attacks in its south-eastern province of Sistan and Baluchestan province.
Pakistan condemned the strikes as a violation of its sovereignty and said that they had killed women and children.
In retaliation, Pakistan launched air strikes against what it called “terrorist separatist groups” in Iran that killed at least nine people.
The Baloch Liberation Army, an ethnic separatist group, issued a statement confirming that strikes had killed some of its members and warning that Pakistan would “pay a price”.
“Now the Baloch Liberation Army will not remain silent. We will avenge it and we announce war on the state of Pakistan,” it said.
The strikes have jeopardised relations between Iran and Pakistan and threatened to cause another flashpoint in the region amid the ongoing Israel-Gaza war and clashes in Iraq, Syria and Yemen.
Here is everything you need to know about the two militant groups at the heart of the tensions.
Who are the Baloch people?
Both militant groups are comprised primarily of members of the Baloch ethnic group, known as Balochs.
There are thought to be around 6.8 million Balochs in Pakistan, and around 2 million in Iran. There is also a sizeable population of Balochs across the Gulf in Oman.
The Balochi language, which is a Western Iranic language, is spoken by about 8 to 9 million people.
Most Baloch people live in the Iranian province of Sistan and Baluchestan and the neighbouring Pakistani province of Balochistan. Both provinces are large and sparsely populated, with a desert climate and mountainous terrain. Their southern coastline stretches from the Gulf of Oman into the Arabian Sea.
The area is rich in precious metals including gold, and is home to large natural gas fields.
What is Baloch nationalism?
Some Balochs in these provinces have campaigned for either more autonomy from Iran and Pakistan or an independent state.
They argue that the central governments of Iran and Pakistan have neglected the Balochs and deprived them of social and political rights.
Baloch nationalists also accuse the Pakistani government of exploiting the rich mineral wealth of Balochistan without fairly compensating the people who live there.
Some nationalists have taken up arms, waging a series of low-level insurgencies against the Pakistani government since the creation of the country in 1947.
Pakistani security forces have attempted to crack down on insurgents. Hundreds of Baloch have protested in the Pakistani capital of Islamabad in recent weeks, accusing security forces of enforced disappearances and extrajudicial killings.
Across the border in Iran, Balochs have also fought against the government for greater autonomy or independence.
Most Balochs are Sunni, and some of the fighting in the region has witnessed sectarian attacks against Shiites.
Shiite-majority Iran is ruled by a theological regime, while an estimated 10-15 per cent of Sunni-majority Pakistan is Shiite.
Two militant Baloch nationalist groups were the target of the recent strikes: Jaish Al Adl and the Baloch Liberation Army.
Who are Jaish Al Adl?
Jaish Al Adl, or Army of Justice, is a Baloch nationalist Sunni militant group.
The group is made up of ethnic Balochs fighting for the independence of Iran's Sistan and Baluchestan.
It is considered a terrorist organisation by Iran and the US among others.
Jaish Al Adl was founded in 2012, primarily by members from another militant group, Jundullah, or Soldiers of God, which was weakened after Iranian security forces arrested many of its members and executed its founder Abdolmalek Rigi in 2010. Jundullah had pledged allegiance to ISIS following that group's capture of Mosul in Iraq in 2014.
Jaish Al Adl has carried out attacks in Iran, but Iranian officials say it has bases across the border in Pakistan. The Pakistani government denies that Jaish Al Adl has an organised presence in the country, but has acknowledged militants may be hiding in remote areas.
The group has frequently attacked Iranian security forces near the Pakistani border, and its members are believed to travel across the Iran-Pakistan border despite efforts to set up checkpoints.
In 2019, Jaish Al Adl claimed responsibility for an attack on the Khash–Zahedan road in Sistan and Baluchestan that killed 27 members of Iran's Islamic Revolutionary Guard Corps.
It has carried out other attacks against Iranian security forces in the province.
A policeman was recently killed in an attack by the group on a checkpoint in Rask County, Iranian media reported.
Who are the Baloch Liberation Army?
The Baloch Liberation Army is one of the most prominent armed separatist groups in Balochistan.
It campaigns for complete independence from Pakistan.
The BLA was designated as a terrorist group by the US in 2019, in a decision welcomed by Pakistan.
The group rejected the announcement at the time, calling it "beyond comprehension and unjustified" in a statement and accusing the US of falling victim to diplomatic "blackmail" by Pakistan.
Last year, the group attacked Chinese engineers working at the port of Gwadar in the province. In 2019, BLA militants took credit for an attack on a hotel in Gwadar popular with business travellers, killing several Pakistani staff and guards.
China has a major footprint in the region, which is a key location in Beijing's multi-billion dollar China Pakistan Economic Corridor. The corridor is part of the Chinese government's global Belt and Road Initiative, which aims to connect China to Europe and Africa via a vast global infrastructure network that passes through Balochistan.
China also operates gold and copper mines in Balochistan and is allied to the Pakistani government.
The BLA has also claimed attacks outside of Balochistan, in the southern city of Karachi, where it attacked the Chinese consulate in 2018 and the Pakistan Stock Exchange Building in 2020.
The group was led by Balach Marri until his death in Afghanistan in 2007, which was seen as a major blow to the group.
The BLA is one of several similarly named armed separatist groups, including the Balochistan Liberation Front, the Balochistan Liberation United Front, and the Baloch Students Organisation (Azad).
The Associated Press and Reuters contributed to this report.
