The United States has again said that Syrian President Bashar al-Assad must step down to allow a political settlement.
Speaking after talks with British Foreign Secretary Philip Hammond in London on Saturday, US Secretary of State John Kerry said that Assad has to go but the timing of his removal should be decided through negotiation, Reuters reported.
Kerry also called on Russia and Iran to use their influence over the Syrian leader to convince him to quit his post.
"We need to get to the negotiation. That is what we're looking for and we hope Russia and Iran, and any other countries with influence, will help to bring about that, because that's what is preventing this crisis from ending," he said.
"We're prepared to negotiate. Is Assad prepared to negotiate, really negotiate? Is Russia prepared to bring him to the table?" he asked.
US officials claim that Russia is engaged in "an imminent enhanced Russian military buildup" in Syria. They say that Russia has deployed heavy equipment, including tanks, helicopters and naval infantry forces to Syria's Latakia airbase.
On Friday, a US military official, who spoke on condition of anonymity, said that four Russian fighter jets had arrived in Syria and were stationed at an airfield near Latakia.
"For the last year and a half we have said Assad has to go, but how long and what the modality is ...that's a decision that has to be made in the context of the Geneva process and negotiation," the top US diplomat stated.
"It doesn't have to be on day one or month one ... there is a process by which all the parties have to come together and reach an understanding of how this can best be achieved," he added.
'US policy in Syria hits dead end'
The Pentagon said on Friday that Washington and Moscow have resumed high-level military contacts to discuss mechanisms to avoid accidental encounters between their forces in Syria.
In an interview with Press TV on Friday, an American foreign policy analyst said the failure of US policy in Syria has prompted Washington to hold talks with Russia over the Syrian crisis.
“Clearly what’s motivating is that the US policy has really hit a dead end,” said James George Jatras, a former US diplomat and adviser to the Senate Republican leadership.
“There was an almost panic in the Senate this week, as the administration testified that after spending tens of millions of dollars to train forces in Syria, they have trained precisely four or five fighters,” he added.
“With the Russians now moving in and strong support for Assad and it’s clear that Assad is going to stay, they really don’t know what else to do at this point,” the analyst noted.