What is the fine-grained topic of the following text: They met on the sidelines of a meeting of Southeast Asian nations in Laos, the second time they have met this month to discuss the Syria plan, which would see Washington and Moscow share intelligence to coordinate air strikes against the al Qaeda-affiliated Nusra Front and prohibit the Syrian air force from attacking moderate rebel groups. Only return the topic.
Discussions between Washington and Moscow to coordinate a Syria plan against al Qaeda-affiliated Nusra Front and to protect moderate rebel groups.