Russia on Tuesday responded to U.S.-hosted peace talks between Armenia and Azerbaijan this week, saying there was “no alternative” to a deal that Moscow signed with the two warring parties in 2020.

Initiatives to lower tensions in the region “are possible above all on the basis of the trilateral documents signed with Russia,” said Kremlin spokesman Dmitry Peskov. “For the moment, there is no other legal basis that would help a resolution. There is no alternative to these trilateral documents.”

Washington is mediating negotiations between Baku and Yerevan this week, seeking to quell recent tensions over the disputed Nagorno-Karabakh enclave. Armenia and Azerbaijan have gone to war twice over the territory in 1990 and 2020, leaving tens of thousands dead, and clashes regularly erupt. 

Tensions spiked again last week over the checkpoint, which Armenia considers a violation of the ceasefire.

Moscow brokered a ceasefire between the two countries after the latest bout of fighting in 2020 and posted peacekeepers along the Lachin corridor. With Russia bogged down in Ukraine and unwilling to strain ties with Azerbaijan's key ally Turkey, the United States and European Union have sought to steer a thaw in ties.