A Syrian cease-fire brokered over the weekend by the United States and Russia went into effect Sept. 12, though it remains to be seen whether it holds.

Pessimism over the agreement’s prospects for success followed soon after it was announced Sept. 10 in Geneva by US Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov. That pessimism is not entirely groundless. Indeed, Russians and Americans see what constitutes the key part of the agreement differently.

For the American party, the key is Russia’s willingness to restrain the forces of Syrian President Bashar al-Assad from conducting air operations over areas held by opposition forces and Jabhat Fatah al-Sham (formerly the al-Qaeda affiliate Jabhat al-Nusra). The Russians, however, pin their hopes on the US ability to ensure the opposition groups Washington has been supporting refrain from violence and separate themselves from Jabhat Fatah al-Sham. Therefore, each party expects that potential violations will by and large come from their opponent’s side.

However, some in Russia think sabotage might come not only from opposition forces and radicals but also from some groups inside the Syrian government. Anton Mardasov, the head of the Department of Middle Eastern Conflicts of the Moscow-based Institute for Innovative Development and one of Russia’s closest observers regarding the Syria crisis, explained the situation to Al-Monitor.