The Islamic State’s safe haven in Sirte, Libya has been “reduced to a single square kilometer,” Secretary of Defense Ash Carter told the Senate Armed Services Committee earlier today.

Carter’s testimony was echoed by Al Bunyan Al Marsoos (“Solid Structure”) operations room, which draws fighters from militias based in Misrata and is allied with Libya’s Government of National Accord (GNA). Al Bunyan Al Marsoos launched an offensive against the Islamic State’s stronghold in May. Earlier today, it posted a map (seen above) showing the jihadists’ shrinking territory.

Al Bunyan Al Marsoos has repeatedly posted versions of this map. The group indicated in mid-August that the jihadists were operating in only a few neighborhoods. That assessment was generally consistent with an infographic produced by the Islamic State’s own Amaq News Agency. The Islamic State has lost even more ground since then.

During his testimony before the Senate, Carter explained that he and other US officials had “expressed concern that if left untended, Libya could be the next ISIL headquarters, as ISIL’s control over the city of Sirte was seen as their contingency plan for where they would go when they lost Raqqa and Mosul.” ISIL (Islamic State of Iraq and the Levant) is the US government’s acronym for the Islamic State.

“But because the President authorized us to act,” Carter’s written testimony continued, “ISIL is now under tremendous pressure there, with its territory in Sirte reduced to a single square kilometer.” Carter also described the Islamic State’s remaining safe haven in the city as “a single neighborhood.”

Indeed, Sirte is so important to the Islamic State that the group’s deceased spokesman, Abu Muhammad al Adnani, mentioned it alongside Raqqa, Syria and Mosul, Iraq in a speech that was released in May — the same month Al Bunyan Al Marsoos began closing in. Raqqa and Mosul are the de facto capitals of the “caliphate” and, as such, the most important cities under the jihadists’ control.

In his speech, titled “That They Live By Proof,” Adnani implicitly conceded that the Islamic State could lose one or all three of these cities. Adnani, who was killed in August, argued that neither the loss of individual leaders, nor the “loss of a city or the loss of land,” would mean that the Islamic State has been defeated as long as the jihadists retained the will to fight. His words were a far cry from the Islamic State’s motto of “remaining and expanding,” which was often evoked during the organization’s rise in power.

Al Bunyan Al Marsoos’ fighters have been receiving American air support as part of “Operation Odyssey Lightning” since Aug. 1. As of Sept. 21, according to United States Africa Command, the US has carried out 161 airstrikes in Sirte. The “precision” bombings often strike enemy fighting positions, weapons, the jihadists’ vehicle-borne improvised explosive devices (VBIEDs), as well as other targets.

At least four Western nations reportedly have special forces inside Libya: France, Italy, the US and UK. They may not all be operating in Sirte. But in addition to the US, press reports indicate that Libya’s special forces are taking part in the offensive.

As the battle for Sirte heated up, Abu Bakr al Baghdadi’s loyalists were forced to dispatch their “martyrs.” As The Long War Journal previously reported, the Islamic State claimed only suicide attack in all of Libya between January and April. But the group claimed 26 “martyrdom operations” in and around Sirte between May and the end of August.

The Islamic State claims that Al Bunyan Al Marsoos has suffered heavy casualties in the past few days. On Sept. 19, Amaq News Agency, which is one of the so-called caliphate’s main propaganda arms, reported that more than 30 militiamen “were killed and dozens wounded during clashes that took place yesterday in the 3rd Neighborhood, east of Sirte city.” Of course, Amaq’s claims are impossible to verify and the media outfit has an incentive to exaggerate its enemies’ casualties. Still, it is possible that Amaq’s report is more or less true, as the two sides are engaged in heavy fighting in close urban corridors. And while the jihadists appear to be confined to a single neighborhood, they are still able to strike in the surrounding areas.

As Al Bunyan Al Marsoos’ men have cleared the Islamic State’s forces block by block, they have posted on social media some of the oddities found in the city. On Sept. 20, for example, the group published on Facebook images of the Islamic State’s “marriage contracts.” As first reported by Agence France-Presse, Baghdadi’s men agreed to give women guns and “explosive belts” in exchange for entering into wedlock.

Other images depict the horrible effects of war on Sirte, including severely damaged buildings and debris strewn throughout the city.

Note: This article contains sentences published in previous Long War Journal reports on the battle for Sirte.

Thomas Joscelyn is a Senior Fellow at the Foundation for Defense of Democracies and the Senior Editor for FDD's Long War Journal.

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