The US has warned of civilian losses in Syria as part of a campaign against the Islamic State group.

Speaking to a US Senate committee, US Air Force Lieutenant General Robert Bales warned that drones, or unmanned aerial vehicles, were a tool for war.

“Drones, as we’ve seen, have the ability to strike a target with pinpoint accuracy and precision, and if we have to go into Syria, we’re going to do it with a drone,” he said.

“We’re going there to protect our interests.

That’s why we’re using them, but we’re also going to have to use them with caution, because we have a lot of innocent people out there.”

He added that the US was working with partners to ensure that any drone strike would be approved in advance.

“This is not just about getting into Syria,” he added.

“It’s about ensuring that we’re not using this technology in a way that might be perceived as indiscriminate.”

And we want to ensure it is not used as a weapon of war.

“On Tuesday, the US said it had conducted 15 air strikes against the group in northern Syria, with six strikes hitting an IS position.

It said a further two strikes were carried out against IS targets in Iraq.

Mr Bales said the US had seen an increase in the number of civilian deaths in Syria, but said the numbers were not known for sure.”

I can’t give you a specific number because we don’t know exactly how many people have been killed or injured,” he told the Senate Armed Services Committee.”

But we know that there are civilians out there who are being targeted and have been targeted.

“On Thursday, Mr Bales also warned that US troops could not operate from the US embassy in Damascus, saying that any attempt to do so could be considered a violation of international law.”

There are clear indications that the Assad regime is using these weapons to deliberately kill civilians, to deliberately harm civilians and to intentionally cause civilian casualties,” he wrote in the State Department’s official annual report.”

Such conduct would constitute a war crime and an affront to the international law of armed conflict.

“The Assad regime’s use of such weapons must be stopped and brought to account.”

He said the use of chemical weapons by the Assad government was an “unprecedented and deliberate use of weapons of mass destruction”.

“These attacks must be condemned and prevented at all costs,” he continued.

“These are acts of war against civilians.”

On Friday, President Donald Trump signed an executive order to extend the use and transfer of military equipment from the United States to the Syrian government.

The order allows the transfer of “all munitions, all armaments, all equipment” including drones, combat helicopters and surveillance aircraft to the military of Syrian President Bashar al-Assad.

In a statement issued after Mr Trump signed the order, the White House said the move “remains in the national security interest of the United Sates”.

“We will continue to closely monitor developments in Syria,” the statement read.

“In the interim, the United State will be exercising its right under international law to assist the Syrian people in their fight against the ISIL group.”

In addition to weapons transfers, the president has authorised the US military to provide up to $1bn in military assistance to the government of Syria.

In his written statement, Mr Trump said he “looks forward to working with the Syrian Government and the opposition to achieve a lasting political settlement in Syria”.

Mr Bairo told senators the Syrian air force had conducted “a number of precision strikes” against IS positions on Thursday.

“A US strike in a Syrian airbase on Thursday morning killed a number of ISIS fighters and their leader in eastern Syria, a commander of the Syrian National Defence Forces, General Saad al-Jassasani,” Mr Bairo said.

The statement also said the air raid killed “a commander of ISIL-linked terrorist groups”.

“Today’s strike also destroyed two ISIL weapons depots and destroyed a large ISIL stockpile,” it added.