U.S. Secretary of State Marco Rubio begins a visit to the Middle East today, Wednesday, as he seeks to reassure Gulf allies concerned about concessions in the agreement reached between President Donald Trump and Iran, including the proposed $300 billion fund, which they view as overly generous toward a regional adversary.

Rubio arrived in Abu Dhabi late on Tuesday, marking the start of a three-day Gulf tour, in what is his first high-level diplomatic mission tied to the agreement reached last week to end the four-month-long U.S.-Israeli war with Iran.

Marco Rubio (AFP).

In response to a question upon his arrival about whether he intends to address allies’ concerns over the agreement, Rubio told reporters, “The matter will certainly be raised during these discussions.” He added that talks would also cover issues not included in the memorandum of understanding.

Rubio has largely been absent from discussions on Iran in recent weeks, while Vice President J.D. Vance led a round of talks with Iranian counterparts earlier this week in Switzerland.

Rubio’s comments during the tour will be closely watched to see how the former outspoken critic of Iran describes the agreement, which many Republicans in Congress have characterized as a form of surrender.

Rubio and Vance, both former U.S. senators, are widely viewed within Republican circles as potential successors to Trump, with party insiders and early polling often framing the race primarily as a contest between the two.

Capitol Building. (AFP)

Rubio’s task is delicate: he must firmly defend the preliminary agreement strongly backed by Trump, while also working to ease concerns among his Gulf counterparts, who are approaching the deal with greater caution.

Despite Gulf leaders calling for a ceasefire throughout the four-month conflict, many were left shocked and disappointed by the terms of the agreement.

Among the countries included in Rubio’s tour are the United Arab Emirates and Kuwait, both of which host strategic U.S. military bases and have previously come under Iranian missile attacks that resulted in civilian casualties.