Iraqi security forces clash with Islamic State group militants on the outskirts of Ramadi, on June 15, 2015. Reuters

The Islamic State group claimed responsibility Wednesday for shooting down an Iraqi fighter plane north of the city of Ramadi, according to statements made on Twitter accounts associated with the extremist organization, Reuters reported. The group said the fighter jet was shot down as it conducted a raid in areas north of the city, seized by Islamic State militants in May.

While the claims by the group, also known as ISIS, have not yet been independently confirmed, a member of an anti-Islamic State Sunni force called Sahwa told Reuters that a Russian-made Su-25 Iraqi fighter jet was seen in flames as it crashed after being shot down north of Ramadi.

The Iraqi military, supported by a U.S.-led coalition and Iranian-backed Shiite militias, has been battling to regain territory from the jihadist group, which currently holds a third of the country as well as significant swathes of neighboring Syria. Ramadi, the capital of Sunni-dominated Anbar province, has become the center of a campaign to halt the group’s advance in Iraq.

The U.S. announced last week that it would be sending 450 more military personnel to assist the Iraqi military in taking back the strategically significant city. "To improve the capabilities and effectiveness of partners on the ground, the president authorized the deployment of up to 450 additional U.S. military personnel to train, advise, and assist Iraqi Security Forces at Taqaddum military base in eastern Anbar province," a statement released by the White House said.

Iraqi leaders have been hoping to mobilize Sunni tribes in Anbar while deploying police units under new leadership in order to retake Ramadi, according to a campaign plan proposed earlier this month by Iraqi Prime Minister Haider al-Abadi.

Part of this campaign has included efforts to ensure that all militias were accountable to Baghdad’s authority, a senior U.S. official told Agence France-Presse. “It’s very important ... that all forces be brought under the command and control of the Iraqi government and the Iraqi prime minister,” he said. “That’s something that’s a fundamental element of the plan.”