The US government has ordered a halt to offshore wind projects being built near the Atlantic coastline, citing fears around security.
Department of the Interior said it was temporarily stopping work on five large developments while it investigates how turbines could interfere with radar and create other risks to east coast cities.
One of the five developments affected is Equinor's Empire Offshore Wind project which will power half a million homes in New York once complete.
In a statement, Equinor said: "The project is more than 60% complete, with trenching, cable-laying and cable pulling ongoing on the US outer continental shelf.
"In total, dozens of vessels, around 1,000 people, and more than a hundred companies in the US and globally have been working in coordination on the Empire Wind project.
"The stop work order threatens the progress of these activities and without a swift solution there may be significant impact to the project.
"Empire and its contractors are complying with the order, safely suspending all ongoing activities related to the Empire Wind Project on the Outer Continental Shelf, with the ability to perform any activities that are necessary to respond to emergency situations and/or to prevent impacts to health, safety, and the environment."
The other impacted developments are off the coast of Virginia, Massachusetts, Rhode Island, and Connecticut.
President Donald Trump, the BBC reports, has long opposed wind energy, questioning its reliability and arguing it drives up costs.
He has attempted to stop all wind projects since returning to office, and Interior Secretary Doug Burgum has said wind farms have no future in the US energy grid.
Renewable energy companies, as well as state leaders, have expressed alarm over the administration's stance.
The Department of the Interior said the pause "addresses emerging national security risks, including the rapid evolution of the relevant adversary technologies, and the vulnerabilities created by large-scale offshore wind projects with proximity near our east coast population centres".
The government specifically references the potential for radar interference "clutter" that can obscure real moving targets or create false ones. It added that a radar's threshold for false-alarm detection could be increased to reduce some clutter, but only at the risk of missing actual targets.
The wind projects could make it difficult to "determine what's friend and foe in our airspace", Interior Secretary Doug Burgum said in an interview with Fox Business on Monday, where he cited drone strikes between Russia and Ukraine and between Iran and Israel as examples.