The Islamic State is likely to continue looking for ways to expand in Afghanistan, the Pentagon said Tuesday in a new report, setting the stage for bloodshed between militant groups competing for influence.

U.S. military officials said the potential emergence of the Islamic State in, which seized broad sections of Iraq and Syria, has “sharply focused” Afghan officials and military leaders. Thus far, U.S. forces have seen evidence of limited recruiting efforts in Afghanistan and noted a few militants rebranding themselves, likely in an attempt to draw media attention, greater resources and more recruits.

“ISIL’s presence and influence in Afghanistan remains in the initial exploratory phase,” the Pentagon report said, using one of the acronyms for the militants. “The Islamic Movement of Uzbekistan has publicly expressed support for ISIL as the leader of the global jihad; however, the Taliban has declared that it will not allow ISIL in Afghanistan.”

The report was released the same day that the Taliban released a letter Islamic State leader Abu Bakr al-Baghdadi warning that if Islamic State militants want to fight in Afghanistan, it must be under the Taliban. Fighting broke out this week in the eastern province Nangahar between Taliban fighters and militants affiliated with the Islamic State.

“The Islamic Emirate of Afghanistan from a brotherhood point of religion wants your goodness and has no intention of interfering in your affairs,” reads the letter, which was sent to journalists on Tuesday. “Reciprocally, we hope and expect the same from you.”

The potential expansion of the Islamic State into Afghanistan has prompted broad and concern and spawned militias operating on their own. None of them at this time pose an existential threat to the government in Kabul, but the Afghan military and police will likely be tested again this year in fighting that killed thousands of Afghan troops last year, the Pentagon report said.

Despite the buzz created by the rift, it’s actually the Haqqani network that remains the greatest threat to U.S., coalition and Afghan forces, the Pentagon report said. Based in Pakistan, it continues to be a “critical enabler” of al-Qaeda.

“The Haqqani Network and affiliated groups share the goals of expelling U.S. and coalition forces, overthrowing the Afghan government, and re-establishing an Islamic Emirate of Afghanistan,” the report said. “The Haqqani Network led the insurgency in the eastern Afghan provinces of Paktika, Paktiya, and Khost, and demonstrated the capability and intent to support and launch high-profile, complex attacks across the country and in the Kabul region.”

There are probably fewer than 100 al-Qaeda members in Afghanistan on a full-time basis, and they remain focused mainly on survival, rather than planning future attacks on the United States, the new Pentagon report said. The remaining members are concentrated largely in the eastern provinces of Kunar and Nuristan, but receive support from the Taliban and “at least tacit support” from some civilians.

Al-Qaeda fighters began to move into other provinces, including Ghazni, Zabul, and Wardak, in the spring and summer, the Pentagon report said.