Washington is considering a Russian proposal of direct military talks regarding the situation in Syria, US Secretary of State John Kerry said as his spokesman struggled to explain the setbacks to US efforts against Islamic State militants in the region.

Reporters grilled deputy State Department spokesman Mark Toner over revelations that only a handful of US-trained “moderate Syrian rebels” remained in the fight. General Lloyd Austin, Head of the US military’s Central Command, testified before the Senate on Wednesday that only “four or five” of the rebels were still active, out of the group of 54 trained by the $500 million US program.

“We don’t challenge that assessment,” Toner said, noting that the program has “fallen short” and “has not, frankly, lived up to what we initially thought.”

However, he rejected suggestions that setbacks in Syria compelled Washington to consider the Russian proposal of direct military talks. “We have made, we believe, gains in the past year,” he said. “Are we there yet? No. Have we done enough? No.”

'Total failure': Only '4 or 5' US-trained rebels are fighting in Syria, US general says http://t.co/IdXhimqouCpic.twitter.com/uSMuJJyu8V — RT America (@RT_America) September 16, 2015

A year after the US launched a campaign against the self-proclaimed Islamic State (IS, formerly ISIS/ISIL) claiming parts of Iraq and Syria, the territory controlled by the group has actually expanded. The coalition has spent nearly $4 billion on more than 50,000 flights and 6,700 air strikes, with IS showing no signs of being significantly affected. The State Department, however, continues to insist that Russian support for the Syrian government is “not a winning strategy” against IS.

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Russia’s foreign minister, Sergey Lavrov, offered to set up direct talks between the US and Russian military representatives about the situation in Syria, Secretary Kerry said. The offer was reportedly made during a telephone conversation between Kerry and Lavrov on Tuesday. The State Department’s readout of the call makes no mention of anything Lavrov said, however, citing only the continued US insistence on overthrowing the government of Syrian president Bashar al-Assad.

“The Russians proposed... that we have military-to-military conversation... to discuss what precisely what will be done to deconflict [sic] with respect to any potential risks that might be run and to have a complete and clear understanding as to the road ahead and what the intentions are,” Kerry told reporters on Wednesday, after meeting with South Africa’s foreign minister.

Kerry described such talks as “vital to avoid misunderstandings, miscalculations (and) not to put ourselves in a predicament where we are supposing something and the supposition is wrong.” He noted that there was a “capacity for cooperation” if Russia’s alleged military buildup in Syria was focused on fighting Islamic State militants, rather than rebel groups fighting against the government.

The Russian foreign ministry confirmed that Syria was the center of attention during the phone conversation between Lavrov and Kerry. “S.V. Lavrov once again emphasized the necessity of creating a united front against the terrorist groups operating in the territory of that country,” the ministry said in a statement.

At the Kremlin, presidential spokesman Dmitry Peskov declined to comment on Kerry’s statements. “For that you should speak to the Foreign Ministry,” he told reporters.

Russia’s UN envoy Vitaly Churkin said that Minister Lavrov will once again clarify Moscow’s position on Syria to Kerry when they meet in New York next week, for the session of the UN General Assembly.

READ MORE: Blame Assad: The world according to State Department

Following the success of the nuclear agreement with Iran, the US hoped that Russia would change its mind and back the Western-led effort to overthrow the Assad government, according to AP. Moscow’s continued support for Damascus has policymakers in Washington “perplexed” and even “flummoxed,” as US media described it.

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In September 2013, citing a sentence from Kerry’s speech, Russia proposed that Syria should turn over all its chemical stockpiles to the UN. The proposal came as Washington threatened to attack Syria over the government’s alleged use of chemical weapons against the US-backed rebels.

“Syria is handing over its chemical weapons under international supervision because of Russia,” President Assad told a Russian news network.

On Tuesday, Russian president Vladimir Putin called on countries to “set aside geopolitical ambitions,” double standards and use of terrorist groups to achieve their political objectives, and unite in fighting the Islamic State militants operating in Iraq and Syria. Israeli Prime Minister Benjamin Netanyahu announced that he would visit Moscow next week, to discuss Syria with Putin.

READ MORE: Western double standards hit Russia's Syrian efforts