In a tweet published Saturday night, President Trump called the proposal to surround New York City with a six-mile-long seawall "costly, foolish & environmentally unfriendly."
The president fired off the tweet one day after the New York Times published a report on the costly barrier.
The Army Corps of Engineers proposed the wall among a series of other solutions to protect the New York-New Jersey Harbor region from severe coastal storms. The seawall will protect against a storm at least the size of Hurricane Sandy.
"A massive 200 Billion Dollar Sea Wall, built around New York to protect it from rare storms, is a costly, foolish & environmentally unfriendly idea that, when needed, probably won’t work anyway. It will also look terrible. Sorry, you’ll just have to get your mops & buckets ready!"
The New York Times said the seawall proposal only addresses storm surges, not flooding from high tides and storm runoff.
The Army Corps estimates the six-mile-long seawall would cost $119 billion, not the $200 billion that Trump suggests. The Corps also estimates the wall's construction could take 25 years.
New York City Mayor Bill de Blasio responded to Trump, also in a tweet, calling the president's "climate denial" deadly.
"We lost 44 of our neighbors in Hurricane Sandy. You should know, you lived here at the time," the mayor tweeted.
Any decision on the seawall appears to be years away. The Corps plans to present a finished proposal to Congress no earlier than 2022, the Times said.