The US is immediately pausing leases for offshore wind energy projects currently being built near the Atlantic coastline, citing security concerns.

In a statement, the Department of the Interior said it was pausing five large-sale projects to look into how windmills could interfere with radar and create other risks to east coast cities.

President Donald Trump has long opposed wind energy, saying it is unreliable and drives up costs, and attempted to stop all projects when he returned to office. 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.

In its statement, 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 five wind farms now on pause are being constructed off the coast of New York, Virginia, Massachusetts, Rhode Island, and Connecticut.

Specifically, the announcement noted that officials are concerned about radar interference "clutter" that can obscure real moving targets or, conversely, 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", 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.

Dominion Energy, the company behind the Virginia wind farm, said its project is far offshore and "does not raise visual impact concerns."

"The project's two pilot turbines have been operating for five years without causing any impacts to national security," it said in a statement.

Dominion saw its share price drop more than 3% after the announcement.

Orsted, the Danish wind energy giant, recorded a 12% drop in its share price, while turbine maker Vestas' stock fell by 2.6%.

Connecticut Governor Ned Lamont, a Democrat, described the pause as an "erratic" move that "will drive up the price of electricity in Connecticut and throughout the region".

"This project is nearing completion and providing good-paying clean energy jobs," he added. "Businesses and residents deserve economic predictability, yet with the administration's constant starts and stops they're left with the opposite."

Earlier in December, a federal judge struck down an attempt by President Trump to ban new wind power projects in the US, calling it "arbitrary and capricious and contrary to law".

On the first day of his administration in January, Trump issued a memorandum halting permits and new leases until a federal review could be undertaken.

Five months later, 17 US states led by New York sued the administration, calling the ban an "existential" threat to the US wind industry.

Demand in the US for energy is expected to significantly expand in the years ahead, driven by the needs of artificial intelligence firms.

Last week, Trump Media, the parent company of Truth Social that is majority-owned by the president, said it was getting into the energy business, announcing a merger with a fusion firm TAE Technologies.