U.S. Secretary of State Marco Rubio is wrapping his up his second and final day at a Southeast Asian security conference with a high-stakes meeting with his Chinese counterpart as tensions grow over issues from trade to security and China’s support for Russia’s war in Ukraine.

Secretary of State Marco Rubio met with Russian Foreign Minister Sergey Lavrov in Malaysia Thursday at a meeting of the Association of Southeast Asian Nations. The meeting put the Russia-Ukraine war at the center of a trip that was meant to strengthen alliances in Southeast Asia.

US Secretary of State Marco Rubio said Thursday that he was working on a possible sit-down in coming days with China’s foreign minister, Wang Yi, on the sidelines of an Asean meeting in Malaysia amid a contentious trade dispute.