Trump has signed an emergency order blocking certain foreign-made power equipment from the US electricity grid, a hit to Chinese suppliers and a win for US security hawks and domestic manufacturers.

• The order bans imports of transformers and other key parts for the main US grid from certain countries, without naming China directly.
• The worry is hidden digital "back doors" in foreign equipment software that could let a hostile country switch off or tamper with the grid.
• AI data centers are driving electricity demand up fast, so a grid failure would now cause far more damage than before.
• China makes about 80% of the world's batteries and solar inverters, and shipped large numbers of big power transformers to the US over the past decade.
• It echoes the earlier US push to shut Huawei and ZTE out of Western mobile networks, which ended with both blacklisted.

Outlook: US utilities will have to find non-Chinese suppliers for grid gear, likely pushing up costs and adding to trade friction with Beijing.