Almost 80 percent of Russia's declared targets in Syria have been in areas not held by Islamic State, a Reuters analysis of Russian Defence Ministry data shows, undermining Moscow's assertions that its aim is to defeat the group.
The majority of strikes, according to the analysis, have instead been in areas held by other groups opposed to Syrian President Bashar al-Assad, which include al Qaeda offshoots but also fighters backed by Washington and its allies.
Defence ministry statements of targets hit by the Russian Air Force and an online archive of Russian military maps show Russia has hit 64 named locations since President Vladimir Putin ordered the first round of air strikes three weeks ago.
Of those targets, a maximum of 15 were in areas held by Islamic State, according to a survey of locations of the rival forces in Syria compiled by the Institute for the Study of War.
"If you look at the map, you can easily understand that they are not fighting Islamic State but other opposition groups," said Alexander Golts, a Moscow-based defense columnist and deputy editor of online newspaper Yezhednevny Zhurnal.
The data supports assertions from Washington and its NATO allies that Russia's intervention in Syria, its biggest military deployment abroad since the collapse of the Soviet Union, is designed to prop up Assad, who flew to Moscow on Tuesday to thank Putin for his support.
Moscow's other possible motives could be to maintain a strategic foothold in the Middle East and showcase itself as a global military power at a time when relations with the West have sunk to a post-Soviet low over the crisis in Ukraine.
Russian officials have rejected the accusations and repeatedly stressed that they are targeting Islamic State, alongside other groups they classify as Islamist terrorists. They say Moscow and the West are fighting a common enemy.
However, the pattern of the strikes in Syria suggests a different picture.
Russia's air force has flown over 780 sorties against almost 800 targets in Syria since Sept. 30. As recently as Monday, its jets hit targets in six named locations, none of which were in areas held by Islamic State, the Reuters analysis showed.
"The main goal of these air strikes is supporting ground offensives by the Syrian army," Golts said.
The Russian defense ministry was not immediately available for comment.
Statements from the United States Central Command show that 84 air strikes by the U.S.-led coalition against Islamic State hit 13 locations in Syria between Sept.30 and Oct. 19.
In contrast to the Russian campaign, the coalition strikes were concentrated in Syria's northern and eastern regions, where Islamic State militants have take control of large swathes of the country.
A senior Western diplomat in New York said 85 percent of Russian air strikes had been against groups not affiliated with Islamic State.
The Reuters analysis only included specific locations named by the Russian Defence Ministry as air force targets in Syria.
A total of four locations could not be found on maps including Russian military documents. But three of them were identified by Russia's defense ministry as being in Syria's western Latakia and Idlib provinces, meaning they were not in Islamic State territory.
The fourth location, Kfaysir, was in the northern Aleppo province where territory is contested between Islamic State, opposition rebels and the Syrian army.
Russia has also hit Islamic State strongholds in Raqqa and Deir ez-Zor where the defense ministry says it has destroyed command centers, training camps and munitions factories.
Backed by Russia's air force, Syrian government forces have launched offensives against rebels in Syria's Homs, Hama, Latakia, Idlib and Aleppo provinces.
The Syrian Observatory for Human Rights monitoring group said Russia's bombing campaign has killed 370 people in the last three weeks, one third of them civilians.
(Additional reporting by Maria Tsvetkova in Moscow, Louis Charbonneau in New York and Vincent Flasseur in London; Editing by Dominic Evans)