Former President George W. Bush reportedly delivered a broadside against his successor’s foreign policies in a closed-door meeting over the weekend, ripping the pending Iran nuclear deal in what may be his most direct criticism to date — as Washington and Tehran resume talks.

Secretary of State John Kerry is meeting Monday with his Iranian counterpart Mohammad Javad Zarif in New York. The U.S. and five world powers are trying to finalize a nuclear deal with Iran by the end of June.

But Bush, according to a report in Bloomberg View, warned that the deal would be bad for U.S. national security. The former president, who rarely criticizes or even comments on the Obama administration in public, was speaking at a closed-door meeting of the Republican Jewish Coalition on Saturday in Las Vegas.

At the session, Bush reportedly warned that new Iranian President Hassan Rouhani appears “smooth,” but said: “You’ve got to ask yourself, is there a new policy or did they just change the spokesman?”