He vows to veto any attempt by Congress to obstruct the deal

President Obama spoke about the “historic” nuclear deal with Iran from the White House on Tuesday as leaders in Tehran and Vienna addressed the international community.

“Today, because America negotiated from a position of strength and principle, we have stopped the spread of nuclear weapons in this region,” Obama said. “Because of this deal, the international community will be able to verify that the Islamic Republic of Iran will not develop a nuclear weapon.”

After months of negotiation between world powers, leaders announced Tuesday that a deal had been reached. In Washington, Obama said the announcement marks one more chapter in the pursuit to a more peaceful world–the next chapter, will begin in Congress where leaders will have an opportunity to parse through the deal over the coming weeks. Congress has 60 days to vote the deal up or down.

Israeli Prime Minister Benjamin Netanyahu maintained his vehement opposition to the deal, calling it a “historic mistake for the world.”

Obama on Tuesday stressed that it would be “irresponsible” to walk away from the nuclear deal, which would require, among other provisions, Iran to remove two-thirds of its installed centrifuges, 98% of its current uranium stockpile, and require the International Atomic Energy Agency to verify Iran’s compliance within the frameworks of the deal. If Iran doesn’t comply, Obama said, any sanctions relief that’s offered under the deal would snap back into place.

“I strongly believe that our national security interest now depends upon preventing Iran from obtaining a nuclear weapon,” Obama said. “No deal means a greater chance of war in the middle east. Moreover, we give nothing up by testing whether or not this problem can be solved peacefully.”

Though Obama was speaking to the American people from the White House State Room on Tuesday morning, he spoke directly to his many skeptics in Congress who believe this deal is the wrong approach on Tuesday when he said he would veto any attempts to block the deal.

“We do not have to accept an inevitable spiral into conflict,” Obama said. “We certainly shouldn’t seek it. And precisely because the stakes are so high, this is not the time for politics and posturing.”

In London, the British Defense Minister Philip Hammond also welcomed the deal but recognised the anxiety of some of Iran’s neighbors in the Middle East. “We recognise the concern in the region about Iran’s historic pattern of regional activity. We will maintain our clear position in support of the Gulf states and against Iranian interference in their internal affairs. We hope, and expect, that this agreement will herald a step-change in Iran’s relations with its neighbours and with the international community,” he said.

By Time