Construction on the 490-km Mountain Valley Pipeline has come to an abrupt halt after an appellate court issued a one sentence stay and did not offer an explanation. Work was halted in the Jefferson National Forest, Virginia.

Pipeline operator Equitrans Midstream said on Tuesday it is evaluating all legal options, including an emergency appeal at the U.S. Supreme Court.

When Mountain Valley started construction in February 2018, Equitrans estimated the project would cost about $3.5 billion and enter service by late 2018.

Federal approval for the project was placed into the text of the budget deal between U.S. President Joe Biden and House of Representatives Speaker Kevin McCarthy.

The pipeline is backed by Democratic West Virginia Senator Joe Manchin, whose vote is often needed since the Democrats hold a slim majority in the Senate.  Manchin said that this new order halting construction "is unlawful and regardless of your position on Mountain Valley Pipeline, it should alarm every American when a court ignores the law."