The Syrian opposition's lead negotiator, Mohamad Alloush, says that US Secretary of State John Kerry has been pressuring the opposition to join the peace talks taking place this week in Geneva.
The opposition has stated that it will only attend if the government first agrees to stop its bombings, to remove blockades, and to release prisoners.
Alloush says that there will be "a big response" to the US, though he did not elaborate.