Pentagon says Syria prepping chemical attack

The US-led coalition said it would look into the report.

Turkish officials late last week said Mattis had reassured them by letter that arms given to the Syrian Kurds would be taken back and that the USA would provide Turkey with a regular list of arms give to the fighters. The series of air attacks, taken in self-defense by US forces, according to the Pentagon, occurred as pro-Assad forces threatened or approached USA -backed Syrian fighters.

Although the focus of United States military operations in the region is the defeat of Isis in its two major strongholds, Mosul in Iraq and Raqqa in Syria, the Trump administration has showed itself willing to act if the Assad regime carries out a major chemical weapons attack.

Asked if Kurdish militia would revert to their pre-Raqqa level of armaments once the fight was over, Mattis responded: "Well, we'll see".

It depends, he said, on the battle and what weapons the Kurdish fighters need.

"You have to play this thing very carefully", Mattis said. The retired four-star Marine general suggested that with so many forces operating in the same area that deconfliction efforts would have to be worked out differently than they have in the past, though how exactly is unclear.

On 6 April, Donald Trump ordered a salvo of 59 Tomahawk missiles against Shayrat base in response to the sarin attack on Khan Sheikhoun.

"If, however, Mr Assad conducts another mass murder attack using chemical weapons, he and his military will pay a heavy price". "We try to end that through diplomatic means". Assad denied any such attack. But Mattis also noted that YPG militants were well-armed even before the US last month made a decision to offer more specialised equipment for its urban assault on ISIL-held city of Raqqa.

Ankara believes weapons used by the YPG will find their way into Kurdistan Workers' Party (PKK) guerillas' hands to fuel their more than three-decade-long insurgency against the Turkish government. The U.S. and the European Union do not share Ankara's concerns regarding the YPG. And as the fight goes on, he said the US will collect weapons and fix them, or take certain weapons back and provide others.

A member of the Kurdish People's Protection Units (YPG) carries a weapon in a Syrian city of Raqqa's eastern al-Sinaa district, on June 21, 2017, during an offensive by US-backed fighters to retake the Islamic State group bastion.

North Atlantic Treaty Organisation ally Turkey, which views the YPG as a threat, has said Mattis assured it in a letter that the United States would eventually take back the weapons it was giving them once Islamic State was defeated.