Rome: The United States will not cooperate militarily with Russia in Syria because Moscow’s strategy is ‘tragically flawed’, US Defence Secretary Ash Carter said on Wednesday in his strongest comments yet on the issue.

However, the United States is willing to hold basic, technical discussions with the Russians to try to secure pilot safety.

‘We are not prepared to cooperate in a strategy which as we explained is flawed, tragically flawed on Russia’s part,’ Carter said during a trip to Rome, renewing US accusations that Russia’s strikes were not focused on Islamic State militants.

Russia launched its air campaign last month saying it would target Islamic State. But its planes have also hit other rebel groups opposed to Syrian President Bashar al-Assad, Moscow’s ally. Some of these groups are backed by Washington.

‘Despite what the Russians say, we have not agreed to cooperate with Russia so long as they continue to pursue a mistaken strategy and hit these targets,’ Carter said.

‘What we will do is continue basic, technical discussions on professional safety procedures for our pilots flying (over) Syria. That is it. We will keep the channel open because it is a matter of security and safety for our pilots.’

The United States has put forward various proposals, including simple safety protocols, such as maintaining a safe distance between US and Russian aircraft and using common radio frequencies for distress calls, officials say, adding they would be similar to regulations found in civil aviation.

Pentagon spokesman Peter Cook said on Tuesday the United States was awaiting a formal response from Russia on the US suggestions.

Russia’s deputy defence minister, Anatoly Antonov, was quoted by the Tass news agency on Tuesday as saying the Russian military agreed in principle with the proposals made by the United States on coordinating military flights.

He said the two countries would hold a second joint video conference on the subject in the ‘coming days’.