You really can't defend them, against a company operating in China, selling direct to consumer.
But, if you put a tariff on the goods, and it makes them more expensive than those bought domestically, you might see people buying those instead.
Reminds me of a story I once saw. The guy that created, and patented the selfie stick was at a trade show, as a spectator. There was a booth selling "The Original" selfie stick. The company was from China, and had made deals with so many retailers, that the guy couldn't go after them all. Essentially, he got the big boom when he released them, and a month later, China flooded the market.