Celebrity activists took to social media in celebration on Sunday as the Obama administration announced it would halt work on the controversial Dakota Access Pipeline.

The U.S. Army Corps of Engineers announced Sunday it would deny an easement that would have allowed the pipeline to cross Lake Oahe, a reservoir on the Missouri River. The $3.7 billion, 1,172-mile long project was set to transport more than 470,000 barrels of oil per day across four states in what supporters said was a far safer and more cost-effective way than transporting the oil by rail.

In a statement, Jo-Ellen Darcy, the Army’s assistant secretary for civil works, vowed that the agency would “explore alternate routes” for the pipeline.

Sunday’s announcement was a major victory for environmentalists and members of the Standing Rock Sioux tribe, who for months had staged protests at the pipeline site in North Dakota, some of which had turned violent.

The announcement was also a victory for celebrity environmental activists who had vigorously opposed the pipeline, including actors Mark Ruffalo and Shailene Woodley, who was arrested at the protest site in October. Just last week, rocker Neil Young penned an open letter to President Obama calling on him to end the violence against protestors at the site.

On Twitter, celebrities including Leonardo DiCaprio, Seth MacFarlane, Katy Perry and others cheered the Obama administration’s action on the pipeline.

Check out their reactions below:

Standing Rock water protectors… well done. The People fought the oil industry, and the People won. Keep it up. — Seth MacFarlane (@SethMacFarlane) December 5, 2016

soooo how many #NoDAPL babies you think are going to be made tonight?! 👅 — Shailene Woodley (@shailenewoodley) December 5, 2016

An incredible example of what we can do when we come together. Proud that #LDF joined the many voices that made our government listen. https://t.co/QO0AqcfaMB — Leonardo DiCaprio (@LeoDiCaprio) December 4, 2016

Stunning victory at StandingRock! When's the last time the federal gov't was defeated by the Native peoples? Inspiration for what's ahead… — Michael Moore (@MMFlint) December 4, 2016

PROOF THAT YOUR VOICE ACTUALLY MATTERS! 🙏🏼🙌🏼💪🏼😭 https://t.co/tAwL0a9y9E — KATY PERRY (@katyperry) December 4, 2016

It's a good time for protesting to work in this country. #standingrock sending everyone lots of big love. — Chelsea Handler (@chelseahandler) December 4, 2016

Bravo Army Corps of Engineers, bravo Standing Rock, bravo Sioux Nation. You've taught us all something of great value. Stand your ground! — Sally Field (@sally_field) December 4, 2016

Power of the people. We can make a difference. Never forget that. #DAPL — Alyssa Milano (@Alyssa_Milano) December 4, 2016

“@Crystal1Johnson: "To have American soldiers to become part of the spiritual warriors is major major move"#DAPLpic.twitter.com/yLhraxATWk” — John Cusack (@johncusack) December 5, 2016

VICTORY!! Grateful to all protestors, veterans who showed up in support. Proud of dear friend @shailenewoodley. 🇺🇸💧🌎 https://t.co/ysGK9eMkXu — Joseph Gordon-Levitt (@hitRECordJoe) December 4, 2016

Just FYI I am taking full responsibility for the Dakota Pipeline victory. I tweeted about it. Thank you. #EmmyforBilly #ThankYouBilly — billy eichner (@billyeichner) December 4, 2016

Undaunted & brave & never giving up. This is the power of Peaceful Protest. As American as it gets. To all involved, I salute you https://t.co/FSM7LRo7em — Sarah Silverman (@SarahKSilverman) December 5, 2016

Follow Daniel Nussbaum on Twitter: @dznussbaum