The US has admitted that mistakes led to a deadly strike on Syrian troops - an incident that highlighted the chaotic situation of a conflict involving multiple factions and forces. Yet it has claimed the strike did not constitute a war crime because the mistake was unintentional.

In September, the US acknowledged that coalition warplanes had carried out airstrikes that led to the deaths of at least 62 troops, injured a further 100 and opened the for an attack by Isis.

On Tuesday, Pentagon officials said the attack, involving aircraft from the UK, US, Denmark and Australia, had been intended to hit Isis forces. The operation was halted following intervention from Russia, which informed the US they were hitting Syrian forces.

Brig Gen Richard Coe claimed that because the mistake was not deliberate or a result of negligence, the attacks were not illegal under international law.

According to USA Today, Mr Coe said the mistake had its genesis in the fact that the forces the coalition warplanes struck, looked like Isis fighters.

“In many ways, these forces looked and acted like the Da’esh forces the coalition has been targeting for the last two years,” he said.

“The decision to strike these targets was made in accordance with the law of armed conflict and the applicable rules of engagement. But we concluded based upon post-strike analysis that a number of “human factors” resulted in incorrect identification of forces on the ground.”

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The Pentagon said that US military officials had already begun to change procedures based on what happened in the September 17 incident. It said that at least 15 people had been killed, though the Russian military said the total number of dead was 62.

“In this instance, we did not rise to the high standard we hold ourselves to, and we must do better than this each and every time,” Lt Gen Jeff Harrigian, commander of US air forces in the Middle East, said in a statement.

The killing of the Syrian forces took place as the US and Russia continued to dispute efforts to bring about a ceasefire in the five-year conflict that has killed up to 500,000 people and displaced - either internally or abroad - 12m.

Each country accused the other of violating terms of the cease-fire.