MOSCOW, September 8. /TASS/. Moscow hopes to achieve progress at talks with the United States on Syria but understands that it is not always possible to achieve it by the anticipated deadlines, Russia’s Foreign Ministry official spokeswoman Maria Zakharova told reporters on Thursday.

"The work has been conducted very thoroughly, we are determined to get a result, but it is not always possible to achieve this within the desired deadline," Zakharova said.

The key obstacle for reaching an agreement with the US on Syria is the failure to separate the moderate opposition from terrorists there. "Breaking the moderate opposition from terrorists is now the main problem," Zakharova said.

The spokeswoman has called for disregarding the latest leaks in the US mass media that claimed that the upcoming talks in Geneva between Russian Foreign Minister Sergey Lavrov and US Secretary of State John Kerry would be final and decisive.

"There is no deep understanding, real assessment or analysis there of what the Russian and American experts are doing," the diplomat noted. "Possibly, the leaks appeared in order to encourage some developments and achieve certain goals," she added.

Over the past months, Russia has been calling on the US to separate the so-called moderate Syrian opposition that enjoys the West’s support from the terrorists of the Islamic State and Jabhat Al-Nusra groups. Foreign Minister Sergey Lavrov has stated many times that UN Security Council’s Resolution 2254 passed in December 2015 says that the ceasefire does not apply to these terrorist groups.