Syria's UN ambassador, Bashar Ja'afari, slammed the United States at the special Security Council meeting.
But he first suggested that its strike against Syrian soldiers last weekend was first an act of aggression and then an act of incompetence because it couldn't tell the difference between Isis and troops fighting Isis.
The US has admitted the strike but said it was a "terrible mistake".
Prime Minister John Key handed over that part of the proceedings to New Zealand ambassador Gerard van Bohemen to chair.
Ja'afari said the Government was shocked at the "brutal aggression launched by American, British, Australian and Danish fighter jets" last weekend.
The attack lasted 50 minutes and there had been two days of reconnaissance flights by drones before the attack.
"American reconnaissance planes, surveillance satellites and intelligence services failed to distinguish between Isis and those fighting Isis. They are no stranger to such failure."
New British Foreign Secretary Boris Johnson made his debut at the Security Council yesterday during the special debate on Syria. Before the meeting began, he mingled for 10 minutes or so with Prime Minister John Key, who he has met on several occasions, and Foreign Minister Murray McCully, who he has met once before.
"John," Johnson began. "I don't think the people of the world are remotely fooled by what is going on in Syria.
"They know that it is not just a civil war. They know that it is a barbaric proxy war, and it is a conflict that is being fed, and nourished, and armed, and abetted, and protracted, and made more hideous, by the actions and inactions of governments in this room.
"And they look to us ... to set aside our differences and any selfish sense of strategic national interest, and to put the people of Syria first.
"And that means recognising that there can be no political process without a genuine ceasefire, and there can be no genuine ceasefire unless there is a genuine political agreement that we can have a transition away from the Assad Government. Because it is the Assad Government that is responsible, that regime is responsible for the vast majority of the 400,000 deaths."