U.S. Defense Secretary Robert Gates says the war in Afghanistan is a "tough pull" (a hard job) but that momentum is shifting toward the United States and its partners.

In a televised interview on Fox News Sunday, Secretary Gates said that although progress against the Taliban is being made in southern Afghanistan, the war effort is moving more slowly than anticipated.

Gates said the increase of U.S. casualties in Afghanistan was expected, especially this summer, and people have been too quick to say the war is going badly.

In the same interview Sunday, the defense secretary also said there is still time to stop Iran from building a nuclear weapon.

Gates said new U.N. sanctions provide a "reasonable chance" of persuading Tehran to end what the U.S. says is its drive to build nuclear bomb.

Gates said the Obama administration will not concede that a nuclear Iran is inevitable.

Iran denies it is seeking a nuclear weapons and says its nuclear program is for peaceful purposes.

Some information for this report was provided by AP and Reuters.