The US and Russia are considering an agreement to share intelligence on groups in Syria, but the Pentagon has expressed apprehension over the deal.
The administration of US President Barack Obama has been pushing forward with an attempt to strike a deal with the Kremlin to fight groups both countries oppose more effectively in Syria.
The administration has not yet publicly shared details of the possible deal with Russia, but it seems one goal is for the two countries to share intelligence regarding groups such as the DAESH terrorist organisation, Al Qaeda affiliates and other groups in Syria, according to US media reports.
However, the Pentagon is uneasy with the proposed deal, and has expressed apprehension on the subject. It wants some assurances from the Kremlin before the deal is signed, including the grounding of the Syrian regime's fighter jets and limiting them to only carrying out humanitarian and medical missions.
The US and Russia have been following opposing stances in the Syrian conflict. Russia backs the Assad regime, while the US-led alliance holds the regime responsible for the civil war in Syria and has pushed for Assad to step down in the past.
US Secretary of State, John Kerry, is likely to visit Moscow on Thursday to take up the Syrian issue – among other matters – with Russian President Vladimir Putin and his counterpart Sergey Lavrov.
State Department Spokesman John Kirby said on Monday that US Secretary of State John Kerry will visit Moscow this week to discuss Syria, Ukraine, Nagorno-Karabakh and other issues with Russian officials.
Kerry will travel to Moscow on Thursday after taking part in Bastille Day celebrations in France, Kirby said.
After visiting Russia Kerry will fly to Luxembourg for bilateral talks, meet with EU foreign ministers in Brussels, and taking part in multilateral meetings in London on Syria and Yemen, he added.
The Washington Post reported Kirby as also saying, "Kerry is 'extremely frustrated.'
"That's one of the reasons why we're going to Moscow, to see if that change is actually going to be possible – if the Russians are going to do what they've said they were going to do."
But US Defense Secretary Ash Carter may not be visiting Moscow with Secretary Kerry, according to US media reports, raising questions about his views on the decision by the Obama administration to move closer to Russia.
Jonathan Eyal, director of British security think tank the Royal United Services Insitute, expressed disdain for the deal on Twitter: