Trouble is brewing as norms against war dissolve.

Presidents Xi Jinping and Donald Trump are preparing for a summit, with both China and the U.S. emphasizing stable ties.

The two leaders are expected to negotiate over rare earth exports and economic tensions while navigating growing friction over Tehran and security in Asia.

Trouble is brewing as norms against war dissolve.

Washington and Beijing do not trust each other. But expect Trump and Xi to remain on message this week, saying friendly things about each other.