"U.S. President Donald Trump complained Thursday that his country's decades-old security treaty with Japan is nonreciprocal, as he steps up pressure on allies to increase defense spending and buy more American products." [2]
It's about buying more American weapons.
[1] https://www.bloomberg.com/news/articles/2025-02-13/trump-tel...
[2] https://english.kyodonews.net/news/2025/03/fd3521d51353-upda...