India and China have reached an agreement on military disengagement along their disputed border, New Delhi said, a step toward reducing frictions between the nuclear-armed neighbors that comes as both countries’ leaders arrive in Russia for a summit.

Four years ago, several soldiers from both sides were killed in a bloody melee. Any thaw between the countries could have global implications.

China and India agreed to allow each others’ troops to patrol the disputed border between the two countries, a significant step toward ending a four-year stalemate as leaders from both nuclear-armed nations possibly meet at a BRICS summit this week.