President Barack Obama spoke to leaders across the Middle East on Tuesday and is sending Defence Secretary Ashton Carter to Israel next week as the United States seeks to ease concerns in the region about the impact of this week's historic Iran nuclear deal.
Just hours after negotiators from the US and five other world powers reached an accord with Iran, President Obama was hitting the phones with Middle East allies, stressing that the US was committed to preventing Iran from obtaining a nuclear weapon.
He spoke to King Salman bin Abdulaziz of Saudi Arabia, Crown Prince Sheikh Mohammed bin Zayed Al Nahyan of the United Arab Emirates and Israeli Prime Minister Benjamin Netanyahu.
The President's global sales pitch is an indication of just how polarising the Iran deal has been and will now likely be seen as a test of US ties with Israel and the Arab world.
Sunni-majority Gulf nations like Saudi Arabia have long raised concerns that any sanctions relief for Shi'ite-majority Iran would catalyse Teheran's destabilising activities in the region.
GREATER CHANCE FOR PEACE NOW
Put simply, no deal means a greater chance of more war in the Middle East. Moreover, we give nothing up by testing whether or not this problem can be solved peacefully. If, in a worst-case scenario, Iran violates the deal, the same options that are available to me today will be available to any US president in the future.
U.S. PRESIDENT BARACK OBAMA
Iran is said to back numerous militant groups across Yemen, Lebanon and Iraq.
Israel's reservations are more direct - the state considers a nuclear Iran an existential threat.
For much of the past 24 hours, the Obama administration has been pushing a two-pronged message on the deal: First, that the US remains committed to the security of its allies. And second, while the agreement may be imperfect, it remains better than the alternative.
Said President Obama in remarks after the pact was announced: "Put simply, no deal means a greater chance of more war in the Middle East. Moreover, we give nothing up by testing whether or not this problem can be solved peacefully.
"If, in a worst-case scenario, Iran violates the deal, the same options that are available to me today will be available to any US president in the future."
Senior administration officials later argued that the world would be better prepared to respond to Iran's nuclear ambitions when the deal's provisions expire in 10 to 15 years.
"We will also have benefited from 15 years of an extensive and comprehensive transparency and verification regime that will allow us not only to monitor Iranian compliance but, again, to look across the entire supply chain of the Iranian nuclear programme and to have access to suspicious sites as necessary," an official said during a conference call with journalists.
How convincing these arguments are, especially to an Israeli government that has frosty ties with the Obama administration, remains unclear.
In Mr Obama's conversation with Mr Netanyahu, the President said the deal "will not diminish our concerns regarding Iran's support for terrorism and threats towards Israel". He added that Mr Carter's visit was an opportunity to continue close consultation on security issues.
In calls with King Salman and Crown Prince Mohammed Al Nahyan, he stressed that the accord will prevent Iran from obtaining a nuclear weapon by cutting off all of the potential pathways to a bomb.
Mr Obama is expected to make more calls to world leaders in the days to come and is also due to meet congressional leaders as lawmakers prepare to debate the deal on Capitol Hill.