Washington (CNN) Assessing his war on ISIS after the group overtook the key Iraqi city of Ramadi, President Barack Obama said in an interview this week his strategy against the terrorists isn't failing.

"I don't think we're losing," Obama said in the Tuesday interview with The Atlantic magazine, which posted online Thursday.

Calling the fall of Ramadi, the capital of Anbar province, a "tactical setback," Obama pinned the blame on poorly trained and organized Iraqi Defense Forces.

"The training of Iraqi security forces, the fortifications, the command-and-control systems are not happening fast enough in Anbar, in the Sunni parts of the country," he told interviewer Jeffrey Goldberg.

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As ISIS takes ground in Sunni-dominated Anbar, the administration has worked to bolster Iraqi security forces, including backing multi-sectarian forces termed "Popular Mobilization Units" that include Shia fighters. Administration officials insist those forces must remain under the control of the central Iraqi government, a proposition that in the past has proven difficult.

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