I hate seeing our nation so weak.

After Kerry’s meeting with Zarif, State Department spokesman John Kirby said they had discussed the nuclear deal but that the secretary had “also raised our concerns over the ongoing crises in Yemen and Syria.”

Kerry is also due to meet Russian Foreign Minister Sergei Lavrov on Sunday, and President Barack Obama will see President Vladimir Putin during a packed UNGA program.

The US diplomatic drive in New York was weakened right out of the gate by the latest news from the battlefield.

On Friday, the Pentagon admitted a 70-strong group of rebels that it had trained to fight the Islamic State as part of a $500 million program had surrendered much of its equipment, including vehicles and munitions, to the Al-Nusra Front.

US Central Command, which oversees the fight against the IS group, is also facing an investigation into reports it had manipulated intelligence reports to paint a rosier picture of the campaign.