Obama: Iran deal is only alternative to more Mideast war

US President Barack Obama speaks during a news conference about the recent nuclear deal reached with Iran, in the East Room of the White House in Washington July 15, 2015. [Photo/Agencies]

WASHINGTON - President Barack Obama, seeking to sell the Iran nuclear deal to skeptical US lawmakers and nervous allies, insisted on Wednesday the landmark agreement was the only alternative to a nuclear arms race and more war in the Middle East.

Obama made his case in a nationally televised news conference responding to critics at home and abroad after Iran and six world powers sealed an accord in Vienna on Tuesday to restrict Tehran's nuclear program in exchange for sanctions relief.

"Without a deal," Obama said, "there would be no limits to Iran's nuclear program and Iran could move closer to a nuclear bomb ... Without a deal, we risk even more war in the Middle East."

Obama, who must still overcome a congressional hurdle to enact the accord, said that if the United States does not seize the opportunity, "future generations will judge us harshly."

The agreement is a triumph for Obama, who has made outreach to America's enemies a hallmark of his presidency, but it is also seen as his biggest foreign policy gamble since taking office in 2009.

In his first public comment, Iran's Supreme Leader, Ayatollah Ali Khamenei, said the deal should be scrutinized and legal procedures taken so the other side does not breach it.

In a letter to Iranian President Hassan Rouhani, Khamenei - whose ultimate backing was critical to securing the agreement - said some of the powers involved in the negotiations "are not trustworthy."

Obama is now spearheading an intense White House push to counter Republican critics in Congress and reassure jittery allies such as Israel and Saudi Arabia.

He sent Vice President Joe Biden to Capitol Hill on Wednesday to corral fellow Democrats who might be wavering.

Defense Secretary Ash Carter will travel next week to Israel and Saudi Arabia.

Critics say the deal contains loopholes, especially in inspection procedures that Iran could exploit, and will provide Tehran with an infusion of unfrozen assets to fund its proxies in sectarian conflicts from Syria to Iraq to Yemen.