The United States just made it much harder for Huawei to do business with American companies, a move that threatens its supply chain and could delay the rollout of 5G services around the world.

It's also a major smartphone supplier, competing with Samsung (SSNLF) and Apple (AAPL), and a leader in 5G technology, the next generation of ultra-fast wireless networks.

"This could set back Huawei's supply chain in the US and potentially delay 5G in China," Edison Lee and Timothy Chau, analysts with brokerage firm Jefferies, said in a note Thursday, calling the scenario a "nightmare" for China's adoption of the new technology.

Beyond China, Huawei has signed dozens of commercial 5G contracts around the world, including 25 in Europe and 10 in the Middle East. It could be harder to fulfill those contracts if Huawei can't buy parts from US suppliers. 

Learn more on: https://www.cnn.com/2019/05/16/tech/huawei-us-5g-rollout/index.html