The US has backed groups against Syrian leader Bashar al-Assad with weapons and training.
But Putin, who is supporting Assad in his fight against both the rebels and Islamic State, said today the backing is contrary to the United Nations charter.
And in a scathing attack on the US support he said many of the weapons have just ended up with ISIS.
In an interview with American media ahead of Putin’s meeting with US president Obama tomorrow, the Russian leader said: “In my opinion, provision of military support to illegal structures runs counter to the principles of modern international law and the United Nations Charter.”
US-Russian relations have slumped to a post-Cold War low over the Ukraine crisis, though the two sides share concerns about the threat posed by Islamic State, while disagreeing on the approach.
Putin says Damascus should be included in international efforts to fight ISIS – a demand the America rejects, and he heavily criticised US plans to train up to 5,400 Syrian rebels to fight the terror organisation.
Read more: express.co.uk