The United States has provided "undisguised support" to "terrorists" in Syria, Deputy Foreign Minister Sergei Ryabkov said Thursday, according to state news agency TASS.
The remarks come as the United States threatened to cut off engagement with Russia over Syria as Washington blames Moscow for escalating violence targeting civilians in Aleppo.
Secretary of State John Kerry reiterated the threat Thursday, saying the US was "on the verge of suspending discussions."
"It’s irrational in the context of the kind of bombing taking place to be sitting there trying to take things seriously," he said at a forum in Washington. "There’s no notion or indication of a seriousness of purpose with what is taking place right now."
Russia in recent weeks has repeatedly accused the US of failing to prevent US-backed rebel groups in Syria from working with al-Qaeda-linked terrorists.
Ryabkov, speaking to reporters in Moscow, denounced a US warning that Syrian militants could attack Russia by saying the US has given such militants an invitation to do that.
Ryabkov was commenting on US State Department spokesman John Kirby's statement the previous day about possible consequences of Russia's continued bombing in Syria.
Kirby told a press briefing in Washington that "extremist groups will continue to exploit the vacuums that are there in Syria to expand their operations, which will include, no question, attacks against Russian interests, perhaps even Russian cities, and Russia will continue to send troops home in body bags."
Ryabkov also said a recent week-long ceasefire in Syria fell apart because the period was too long. He suggested temporary 48-hour ceasefires because terrorist groups took advantage of the truce to regroup and replenish their supplies.