I feel like a lot of people are really getting stuck on the Trump stuff and missing Buffetts core argument. Here's a pretty simple guy:

When the US has a trade deficit with China, it tries to balance that out by issuing debt in the form of treasuries.

As more treasuries get issued to foreign nations, the risk to American sovereignty increases. People really forget Japan's blitz on US real estate and businesses in the 80s and the drastic actions of that era the US took to knee-cap Japan.

American sovereignty is a matter of geography, firepower, culture, and law. It’s not easy to threaten.

And private trade deficits are not balanced by sovereign debt, they are balanced by private debt and foreign direct investment, which don’t threaten sovereignty.

The 1990s U.S. reaction to Japanese business success was primarily driven by popular xenophobia, not economic analysis. It was resolved by the dotcom bubble, an explosion of American innovation that changed the conversation. Not by government policy.