US Secretary of State Marco Rubio begins a Middle East tour in earnest on Wednesday, seeking to reassure Gulf allies who view concessions in President Donald Trump’s Iran deal that include a proposed $300 billion fund as too generous to a regional foe, Reuters reports.

Arriving in Abu Dhabi late on Tuesday for a three-day Gulf trip, Rubio is undertaking his first high-level diplomatic mission on the agreement reached last week to end the four-month-old US-Israeli war with Iran.

Asked on arrival if he planned to address allies’ disquiet with the accord, Rubio told reporters: “That most certainly will come up in these discussions.”

He said they would also discuss issues not covered by the memorandum of understanding.