United States Defense Secretary Ashton Carter on Wednesday accused Russia of inflaming Syria's civil war, saying Moscow's military involvement in the war-torn nation was "doomed to fail", reported the AFP news agency.
Speaking to reporters at the Pentagon hours after Russia launched its first airstrikes in Syria, Carter said Moscow's entry into the bloody conflict was akin to "pouring gasoline on the fire."
"The Russian approach here is doomed to fail," Carter said, according to AFP. "I hope that they come over to a point of view where they try to pursue their objectives in a different way that makes more sense."
Earlier on Wednesday, American officials said Russian warplanes had carried out strikes in Homs province, while a Syrian security source and state media said Hama province was also hit.
Russia only gave the United States an hour's warning ahead of the strikes and did not specify where they would occur, riling many in the Pentagon who had been hoping for clearer and more detailed lines of communication.
An Israeli military source told Arutz Sheva earlier Wednesday that Israel, too, had been notified in advance, via a mechanism reached between Jerusalem and Moscow during Prime Minister Binyamin Netanyahu's recent meeting with Russian President Vladimir Putin.
That arrangement was reached after Putin acknowledged Israel's vital security interests in Syria, and agreed to coordinate his own country's efforts there with the Israeli government to avoid any accidental clashes between the two.
National Security Adviser Yossi Cohen was also notified an hour in advance, the source said.
The Pentagon has repeatedly warned of the need for "deconfliction" to ensure coalition and Russian planes don't inadvertently cross paths.
Russian involvement in the Syrian conflict was being seen as a victory for Syrian President Bashar Al-Assad, who invited the Russians to join his battle to cling on to power, and a defeat for the United States, which has demanded he step down.
Though Russia said it was attacking Islamic State forces, Carter said all evidence indicated that the extremist group was not the target of Wednesday's strikes.
"It does appear (the strikes) were in areas where there were probably not ISIL forces," Carter said, using an alternative acronym for the Islamic State (ISIS) group.
Separately, a senior defense official said the strikes appeared to be in support of the Syrian opposition.
The defense official, speaking on condition of anonymity, told AFP the targets were the same ones Russian reconnaissance craft had flown over in recent days.
The Russian defense ministry, however, said its fighter jets carried out 20 flights in Syria, striking "eight Islamic State targets" including a command post held by the jihadist group.
Carter’s remarks come amid continued tension between Russia and the United States over Russia’s growing military involvement in Syria.
The United States was so concerned about reports of Russia’s increased presence in Syria that Secretary of State John Kerry phoned his Russian counterpart Sergei Lavrov a total of three times in ten days to discuss the situation.