Defense Secretary Mattis suggests sticking with Iran nuclear deal U.S. Secretary of Defense James Mattis testifies before a Senate Armed Services Committee hearing on the Political and Security Situation in Afghanistan on Capitol Hill in Washington U.S. October 3 2017 WASHINGTON (Reuters) OCT. 3, 2017  - U.S. Defense Secretary Jim Mattis said on Tuesday the United States should consider staying in the Iran nuclear deal unless it were proven Tehran that was not abiding by the agreement or that it was not in the U.S. national interest to do so. Mattis said he supported U.S. President Donald Trump’s review of the agreement curbing Iran’s nuclear program. Trump is weighing whether the deal serves U.S. security interests as he faces a mid-October deadline for certifying that Iran is complying with the pact, a decision that could sink an agreement strongly supported by the other powers that negotiated it. “If we can confirm that Iran is living by the agreement, if we...