One is a band of separatists fighting for independence from Pakistan. The other is a feared group of Islamists bent on killing Shi'ite Muslims whom they see as infidels.
The two could not be more different in their goals and tactics. But in Pakistan's volatile, resource-rich province of Baluchistan, separatists have teamed up with radical Sunni Muslims in their fight against the Pakistani government.
The unlikely but dangerous alliance poses a new, unexpected challenge for Pakistan, already plagued by a growing Taliban insurgency on its western Afghan border.
"There is definitely coordination," said Baluch Home Minister Mir Sarfaraz Ahmed Bugti. "Both militant groups share the common goal of fighting against the state."
The separatist rebels are considered less hardline compared with other groups, focusing on their political goal of independence.
They do not use religion as a rallying cry but accuse the government of stealing the province's gas and mineral wealth to the benefit of richer, more powerful provinces. They also accuse security forces of widespread rights abuses and cracking down on any forms of dissent.
Lashkar-e-Jhangvi (LeJ), on the other hand, is a hardline group that specialises in attacks against minority Shi'ite Muslims. It believes Shi'ites deserve to die and should be exterminated.
"The two militant groups have been sharing tactical coordination in carrying out major attacks," a senior security official in Baluchistan told Reuters, requesting anonymity.
He said the LeJ had been spotted recruiting fighters among ethnic Baluch. It operates bases in the same area as the separatist rebels, an arrangement which has helped turn them into natural allies.
Baluch separatists have also adopted an LeJ tactic of deploying small children to infiltrate difficult targets and place bombs.
In a recent example of a coordinated attack, a bomb struck a security car on January 10, creating a diversion for a subsequent blast in a Shi'ite enclave which killed more than 100 people.
"It's not a formal pact or alliance, but tactical cooperation," the security official said. "They help each other to coordinate attacks and extend logistical support, for instance by providing cars to carry out explosions."
Baluch pro-independence activists have dismissed any link to the LeJ as state propaganda designed to tarnish their image.
"No such evidence has ever been provided," said Malik Siraj Akbar, an activist and journalist who now lives in Washington.
LITTLE KNOWN CONFLICT
In Islamabad, Prime Minister Nawaz Sharif wants to strike a peace deal with the Pakistani Taliban to end years of fighting in the ethnic Pashtun belt on its northwest frontier with Afghanistan.
But peace negotiations broke down last month, raising speculation that Sharif might opt for all-out military action against Taliban hideouts in the lawless North Waziristan region.
In Baluchistan, to the south of the Pakistani Taliban hot spots, sectarian and separatist violence remains largely unknown to the outside world.
A thinly populated land of deserts and mountains, Baluchistan borders Afghanistan and Iran and is virtually sealed off to foreigners. Getting reliable information is difficult and few officials speak on the record to reporters.
Rebels believe the rest of Pakistan treats them like a colony. They have fought for their own independent secular homeland for decades. In response, security forces have waged a lengthy counter-insurgency to try to quash them.
The last few months have seen a particularly sharp rise in coordinated attacks, causing hundreds of casualties among civilians and security forces, officials said.
"Both are feeding on poverty and extremism rampant in Baluchistan," another security official said. "They may be divergent ideology-wise ... but both are pitched against security forces."