The Islamic State group, also known as ISIS, has issued new threats to U.S. soldiers in Iraq, apparently infuriated by the lack of resistance they have faced from locals.

The warnings came through encrypted social media application Telegram, where the jihadists and their supporters have established a number of channels capable of transmitting information without detection. The messages, which were quoted Thursday by data mining news site Vocativ came specifically in response to the U.S. military presence in the former ISIS stronghold of Ramadi. The central Iraqi city was one of many that were captured by the group in 2014, but it was retaken last year by Iraqi troops, Sunni Muslim tribal fighters and Shiite Muslim militias.

ISIS sympathizers were reportedly angry that up to 60 U.S. soldiers were recently seen being escorted around Anbar University by Iraqi security forces and tribes.

“They tour and walk inside the university like it is their own land,” one user in the channel posted, according to Vocativ. "Wake up and attack them.” A user in the same channel complained earlier this month that “Americans are walking freely” in the city and that “civilians are greeting them, taking pictures and laughing with them.”

While fleeing last year, surviving ISIS militants blew up bridges and reportedly set up camp on the outskirts of the city. Fighters have occasionally tried to return. Earlier this month, Iraqi forces thwarted an ISIS attack from the west of Ramadi, resulting in a number of casualties for the jihadists, according to local media. To ensure ISIS did not make a comeback, the U.S. military has maintained a presence, assisting local forces. This role escalated from air support to a ground deployment, according to statements by Iraqi Ummah Party leader Mithal al-Alusi published earlier this week by London-based newspaper al-Quds al-Arabi. ISIS has reportedly used loose networks of sympathizers to monitor the U.S.' movements.

In ISIS' absence, the U.N. estimated that nearly all 400,000 of Ramadi's residents have returned. The majority Sunni Muslim city reportedly offered the jihadists support when they first arrived, according to Middle East Eye. This was largely due to the poor economic situation and sectarian bitterness that existed between the city's residents and the government, which was largely Shiite Muslim. The rampant destruction and lack of improvement offered by ISIS, however, has led a number of the residents to reportedly welcome U.S. in the city for the second time in a decade.

Ramadi, along with the Anbar region as a whole, was once a hotbed of anti-U.S. sentiment and sympathy for jihadist ideology. These sentiments, exacerbated by the 2003 U.S. invasion of Iraq and toppling of President Saddam Hussein, gave rise to groups such as al-Qaeda in Iraq, which went on to become the Islamic State of Iraq, and then ISIS. Al-Qaeda in Iraq waged a violent campaign of attacks against both U.S. forces and the local Shiite Muslim community, before gathering the strength to take major cities such as Ramadi, Fallujah and Mosul.

These victories were ultimately reversed and the jihadists were expelled from most major cities with the notable exception of Mosul, by far the jihadists' largest stronghold. In August, Iraq launched an operation with assistance from the U.S., Kurdish forces and Iran-backed Shiite militias to oust the group from Mosul and has since secured over half the city.