In the long run, balance is necessary, the surplus is acceptable, and the deficit will be miserable.
The advantage of the surplus is that China exports more things to buy imports and earns a lot of foreign exchange, which seems to be a good thing in the short term, but foreign exchange is paper, American paper, and people can buy things at will, but it is not.
The deficit will be miserable, and we can only buy foreign things, but not domestic industries. If we buy foreign things and don't support domestic ones, domestic industries can only close down. Without basic industries, the country can't sell anything to make money, let alone produce high-quality steel, buy foreign technology and deploy military industry, and the country will die.