President Donald Trump declared a national emergency to block some foreign equipment used in U.S. electricity infrastructure. 

In an executive order signed Wednesday, Trump said foreign supply of electrical equipment “constitutes an unusual and extraordinary threat” to national security. In response, the order restricts the purchase and installation of foreign-made components for electrical infrastructure if that equipment would pose a risk to grid security. 

The order delegates the authority to Energy Secretary Chris Wright, in coordination with other officials, to determine if the equipment poses such a risk. 

The order, which doesn't single out any countries or specify any threats, applies to a variety of infrastructure, including substations, transformers, inverters that are used in renewable energy, battery storage systems and generators.