Kerry says IS 'on road' to defeat despite claims of terror outfit spreading beyond Middle East

The United States' strategy to take on the Islamic State (IS) in Iraq and Syria is working, Secretary of State John Kerry and a top White House official said amid concerns that the U.S. needed to do more to defeat the terror group following the killing of two hostages.

Despite warnings from other corners of the Obama administration that the terror network was in fact spreading, Kerry said on Sunday that the U.S.-led coalition was "on the road" to defeating the IS in Iraq and Syria, reported Fox News.

Kerry argued that the coalition forces had retaken 22 percent of the populated areas that were previously controlled by the IS in the region "without launching what we would call a major offensive."

The statement came just days after Lieutenant General Vincent Stewart, director of the Defense Intelligence Agency, provided a "grim assessment" of the group's evolution in testimony to the House Armed Services Committee.

Stewart had warned that with the help of affiliates in Algeria, Egypt and Libya, the group is beginning to assemble a growing international footprint that includes ungoverned and under governed areas.

Defense secretary nominee Ashton Carter, who had his confirmation hearing on Wednesday, also told the Congress that he is aware of reports that IS may try to make inroads into Afghanistan.