SAN FRANCISCO (AP) — A federal judge has blocked President Donald Trump from building key sections of his border wall with money secured under his declaration of a national emergency, delivering what may prove a temporary setback on one of his highest priorities.

U.S. District Judge Haywood Gilliam Jr.’s order, issued Friday, prevents work from beginning on two of the highest-priority, Pentagon-funded wall projects — one spanning 46 miles (74 kilometers) in New Mexico and another covering 5 miles (8 kilometers) in Yuma, Arizona.

On Saturday, Trump pledged to file an expedited appeal of the ruling.

Trump, who is visiting Japan, tweeted: “Another activist Obama appointed judge has just ruled against us on a section of the Southern Wall that is already under construction. This is a ruling against Border Security and in favor of crime, drugs and human trafficking. We are asking for an expedited appeal!”

While Gilliam’s order applied only to those first-in-line projects, the judge made clear that he felt the challengers were likely to prevail at trial on their argument that the president was wrongly ignoring Congress’ wishes by diverting Defense Department money.

“Congress’s ‘absolute’ control over federal expenditures_even when that control may frustrate the desires of the Executive Branch regarding initiatives it views as important_is not a bug in our constitutional system. It is a feature of that system, and an essential one,” he wrote in his 56-page opinion.