According to the White House, US National Security Adviser Jake Sullivan met with Saudi Crown Prince Mohammed bin Salman on Tuesday about Iran and ways to stop the Yemen war.

The request comes after China recently engineered an agreement to reestablish relations between Saudi Arabia and Iran, the Middle East’s two most powerful regional powers, a process that the US was largely excluded from.

The foreign ministers of Iran and Saudi Arabia met in Beijing last week after agreeing to end their diplomatic rift following years of hostility that fuelled conflicts across the Middle East.

“Mr. Sullivan and Crown Prince Salman also discussed broader trends toward de-escalation in the region, while underscoring the need to maintain deterrence against threats from Iran and elsewhere. Mr. Sullivan reaffirmed President (Joe) Biden’s unwavering commitment to ensure Iran can never acquire a nuclear weapon,” the White House said in a statement late on Tuesday.

Saudi Arabia and Iran, the Gulf’s dominant Sunni Muslim and Shi’ite Muslim powers respectively, have said they would launch arrangements to reopen embassies and consulates within the two-month period stipulated in their deal brokered by China.

Beijing’s role was seen by some experts as signalling a loss of influence by the United States with Saudi Arabia, amid tensions between the long-time allies over a range of issues, including human rights and Saudi oil production cuts.

Saudi and Omani delegations held talks with Houthi officials in Yemen’s capital Sanaa on Sunday, as Riyadh seeks a permanent ceasefire to end its military involvement in the country’s long-running war.

Yemen’s war is seen as one of several proxy battles between Iran and Saudi Arabia. The Houthis, aligned with Iran, ousted a Saudi-backed government from Sanaa in late 2014, and have de facto control of north Yemen.