The US has refused visas to some members of the Iranian president's delegation ahead of the UN General Assembly, a hardball move that piles pressure on Iran but risks souring any talks.

• Iran's president arrives in New York with only part of his team, since some officials were denied entry and have to fly home.
• The move looks aimed at rattling Iran rather than at the individuals themselves, who are not accused of anything specific.
• Trump is using the snub as a pressure tactic to push Iran toward a negotiated deal on his terms.
• It is a petty, deliberately humiliating step, but it could strengthen Washington's hand at the bargaining table.

Outlook: Expect Iran to protest loudly while sideline talks at the UN go ahead with a weakened Iranian delegation.