US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov have agreed to increase cooperation between intelligence services on Isis (now known as the Islamic State), despite divisions over the Ukraine crisis.
Washington and Moscow's top diplomats spoke in Paris following talks over areas of coordination despite a post-Cold War low in relations between the two over Russia's participation in unrest in Ukraine.
"We both recognise the need to destroy and ultimately defeat Isil [another term for theI Islamic State], to degrade their efforts and ultimately to defeat them," Kerry told a news conference.
"No decent country by any definition could support the horrors that are perpetrated by Isil, and no civilised country should shirk its responsibility to stand up and be part of the effort to stamp out this disease."
Kerry said that the two powers had a "major responsibility" to cooperate on various issues and had agreed to "intensify intelligence cooperation with respect to Isil and other counterterrorism challenges of the region".
The secretary of state said that Moscow was to look into the possibility of doing more to arm and train Iraqi forces but did not speak on Russian cooperation with the US-led coalition conducting air strikes against the terror group.
Russia has so far refused to join the coalition because of suspicions that the ultimate aim of the operation is to remove Russian ally Bashar al-Assad from rule in Syria and Moscow has insisted that Syrian government approval should have been obtained before strikes.
The common ground between the US and Russia against IS is found in the make-up of the group's foreign fighters.
"There may be as many as 500 or more from Russia," Kerry said.
Many Russian separatists from Chechnya and Dagestan in the North Caucasus are believed to have flocked to Syria and Iraq to fight for the group which seeks to expand its caliphate straddling the Iraqi-Syrian border.