Obama challenges Iran deal critics to come up with an alternative

"What I haven't heard is: what is your preferred alternative," Obama told critics during a White House news conference.

"And I haven't heard that. And the reason is because there really are only two alternatives here: either the issue of Iran obtaining a nuclear weapon is resolved diplomatically through a negotiation or it's resolved through force, through war. Those are the options," Obama said.

"I share the concerns of Israel, (the) Saudis, Gulf partners about Iran shipping arms and causing conflict and chaos in the region," Obama added. "And that's why I've said to them, 'Let's double down and partner much more effectively to improve our intelligence capacity and our interdiction capacity so that fewer of those arms shipments are getting through the net," Obama said.

(Reporting by Jeff Mason, Lisa Lambert, Roberta Rampton and Will Dunham; Editing by Sandra Maler)