Alarm over Myanmar’s still-unfolding deadly civil strife, including an armed attack on an aid convoy, and China’s aggressive actions in the disputed South China Sea are expected to challenge Southeast Asian leaders’ commitments to non-interference and consensus decision-making as they meet in Indonesia this week.

Top diplomats of the Association of Southeast Asian Nations convened Tuesday in the resort town of Labuan Bajo to finalize the agenda ahead of the two-day summit of the 10-nation bloc’s heads of state.

The United States and China are not part of the twice-yearly summit, but their escalating rivalry looms large over the high-profile Asian gathering. Beijing has warned that U.S. efforts to strengthen security alliances and intensify combat-readiness drills with Asian allies would endanger regional stability.