U.S. Defense Secretary Leon Panetta says Iran is laying the groundwork for making nuclear weapons someday, but is not yet building a bomb and called for continued diplomatic and economic pressure to persuade Tehran not to take that step.

As he has previously, Panetta cautioned against a unilateral strike by Israel against Iran's nuclear facilities, saying the action could trigger Iranian retaliation against U.S. forces in the region. "We have common cause here" with Israel, he said. "And the better approach is for us to work together."

Panetta's recent remarks on CBS' Face the Nation reflect the long-held view of the Obama administration that Iran is not yet committed to building a nuclear arsenal, only to creating the industrial and scientific capacity to allow one if its leaders to decide to take that final step.

The comments suggest the White House's assessment of Iran's nuclear strategy has not changed in recent months, despite warnings from advocates of military action that time is running out to prevent Tehran from becoming a nuclear-armed state, AP reported.