Keith Bradsher

The relationship is at one of its tensest moments in years.

Both sides have threatened measures bordering on economic warfare against each other.

There's an urgency to resolving these issues at the meeting on Thursday in South Korea between the two countries' top leaders.

Here in Beijing, everyone is watching to see can they reach some kind of a deal that pulls both countries back from the brink.

The United States wants China to start buying soybeans again.

China has a boycott against American soybeans right now because of its unhappiness with American policies.

The United States wants China to stop shipping the chemicals that are used in Mexico and Latin America to make fentanyl.

China wants the United States to allow it to buy any kinds of semiconductors it wants, including some of the most advanced semiconductors used in artificial intelligence and high-performance military systems.

And China in particular wants America to distance itself from Taiwan, although America depends enormously on Taiwan for semiconductors.

But hanging over all of these issues

is a big debate over rare earth metals.

China is threatening to cut off much of the world's supply, and it's saying that it will block any effort outside of China to manufacture rare earths and rare earth magnets in competition with China.

Rare earths are very important these days.

They are used all over the economy, whether it's cars, computer chips, fighter jets, missiles.

China controls the materials, rare earth metals, for making them anywhere in the world.

And it has put already in April some export controls on supplying those materials.

And on October 9th, China said, we're going to put a lot more restrictions on these.

China is expanding its restrictions on rare earths exports.

The new rules do three things.

One, they prevent the West from being able to build its own mines and refineries and magnet factories, or at least they make it much more difficult for the West to do that.