WASHINGTON—The top U.S. diplomat for East Asia will visit Indonesia, Malaysia, Singapore, and Thailand from the weekend after President Joe Biden pledged stepped up engagement with Southeast Asia, a key battleground in his contest for influence with China. Daniel Kritenbrink, the assistant secretary of state for East Asia, will be in the region from Saturday until Dec. 4, a State Department statement said. Kritenbrink would “reaffirm the U.S. commitment to work together … to tackle the most serious global and regional challenges” and stress U.S. support for “a rules-based order in the Indo-Pacific,” it said, a reference to the Chinese regime’s increasingly aggressive behavior in the region, which Washington has repeatedly denounced as “coercive.” Kritenbrink will discuss human rights “challenges,” seek to bolster cooperation on climate change and discuss ways to pressure Burma’s (also known as Myanmar) military government to cease violence and allow unhindered humanitarian access, the statement said. …