The US is not ready to collaborate with Russia on a military level against the Islamic State group, the US defense secretary James Mattis has said.
"We are not in a position right now to collaborate on a military level.
"Our political leaders will engage and try to find common ground.
"Russia is going to have to prove itself first, and live up to the commitments they have made in the Russia-NATO agreement."
Meanwhile, the Defence Secretary has told Forces News that Britain is "serious" about expecting its NATO allies to all spend 2% of GDP on defence (see above).
Sir Michael Fallon MP is backing the tough stance voiced by US Defense Secretary on spending and said he hoped it would encourage other nations to meet the target.
James Mattis said the US could "moderate" its commitment to NATO if other countries did not contribute the same amount.
Mr Fallon said: "We all agreed to spend two per cent of our wealth on defence - we agreed that over two and a half years ago.
"Britain meets that target and we expect other allies to meet it as well.
"America is serious about this, and so are we."
When asked about the British contribution in the fight against the Islamic State group, Mr Fallon confirmed UK ground troops would not be deployed, but that air strikes would continue in the Middle East as part of Operation Shader.