Across Afghanistan’s eastern border, in Pakistan’s tribal areas, lies one of the most formidable obstacles to the success of the U.S. strategy in the region: the Haqqani network.

The insurgent group was part of the CIA- and Pakistan-backed mujaheddin alliance that fought against the Soviet occupation of Afghanistan in the 1980s, and its founder, Jalaluddin Haqqani, served as a minister in the Taliban government before its fall in 2001.

Today, the Haqqani network is considered the most dangerous insurgent force fighting U.S. troops in eastern Afghanistan. It has maintained ties with militant organizations spanning the border, including al-Qaeda, part of an alliance that has helped make the Haqqani group particularly worrisome for U.S. officials.

Still, according to a new and deeply researched study, the U.S. assessment of that alliance and of Haqqani’s activities in Afghanistan may very well underestimate the role that the network has played in the spread of global jihad, as well as the danger it poses to American interests more broadly.

Using old jihadist magazines and digital videos as resources, the study from the Combating Terrorism Center concludes that since the 1980s, the Haqqani network has provided not only safe haven for al-Qaeda fighters, but training, propaganda support, networking opportunities and other resources.

The Haqqani network “has been more important to the development and sustainment of al-Qa’ida and the global jihad than any other single actor or group,” concludes the study from the CTC, an independent, privately funded research center at the U.S. Military Academy at West Point.

The study notes that in the early 1990s, when Osama bin Laden was settling in Sudan, Jalaluddin Haqqani published communiqués and requests for assistance for al-Qaeda affiliates in Africa, a rare attempt to aid a non-Afghan organization.

After bin Laden relocated to Afghanistan and began making provocative statements against the West – activities that the Taliban government initially viewed as endangering its own existence and tried to stop – Haqqani allowed the al-Qaeda leader to use its territory in eastern Afghanistan to organize calls for global jihad.

Despite its alliance with al-Qaeda, the network, now led by Jalaluddin Haqqani’s son, Sirajuddin, has long been seen by U.S. intelligence as less ideologically driven and more concerned with retaining power, wealth and influence among other Afghan insurgent factions in the region, and has “consciously portrayed itself as a local actor preoccupied with local concerns,” the CTC study says.

If anything, recent events may have brought al-Qaeda and the Haqqani network closer together, their ambitions more in line. With drone strikes on the network’s base in North Waziristan, it likely has a sense of shared suffering with senior al-Qaeda leaders.

In part because of that shared affinity, the CTC study finds, it would be a mistake for U.S. policymakers to underestimate the impact of Haqqani network beyond Afghanistan’s borders.

“U.S. efforts to disrupt and degrade [al-Qarda] today … are just as much about dismantling [al-Qaeda] as they are about degrading the Haqqani network,” it concludes.

Among other materials, the study’s authors reviewed the jihadist magazines; a series of digital videos produced by the Haqqani network since 2001; and Arabic-language memoirs written by current and former members of al-Qaeda and other foreign fighters in Afghanistan.

You can read the full study here.