FILE–In this Feb. 7, 2017, file photo, Karen Shore holds up a sign outside of the 9th U.S. Circuit Court of Appeals in San Francisco, Calif. A ruling Monday, June 12, 2017, from a unanimous three-judge panel of the 9th U.S. Circuit Court of Appeals deals the administration another legal defeat as the Supreme Court considers a separate case on the issue. (Jeff Chiu, file/Associated Press)

SEATTLE — Another U.S. appeals court stomped on President Donald Trump’s revised travel ban Monday, saying the administration violated federal immigration law and failed to provide a valid reason for keeping people from six mostly Muslim nations from coming to the country.

The decision by a unanimous three-judge panel of the San Francisco-based 9th U.S. Circuit Court of Appeals helps keep the travel ban blocked and deals Trump a second big legal defeat on the policy in less than three weeks.

The administration said it would seek further review at the U.S. Supreme Court, as it has already done with a ruling against the travel ban by another appeals court last month. The high court is likely to consider the cases in tandem.

Attorney General Jeff Sessions insisted the new decision would harm national security — an argument the judges rejected.

“The executive branch is entrusted with the responsibility to keep the country safe under Article II of the Constitution,” Sessions said in a written statement. “Unfortunately, this injunction prevents the president from fully carrying out his Article II duties and has a chilling effect on security operations overall.”

Hawaii Attorney General Doug Chin, who sued to stop the travel ban, said the 9th Circuit ruling “really shows that we have three branches of government and that there are checks and balances. … So to me, this is everything that we learned in social studies in high school just coming to play exactly the way it should.”

The 4th U.S. Circuit Court of Appeals in Virginia last month found the 90-day ban unconstitutional, saying it was “steeped in animus and directed at a single religious group” rather than necessary for national security. It…