Tim Kaine asks for secret White House memo describing the war powers Trump believes he has
U.S. President Donald Trump at the Pentagon in Washington, U.S., January 27, 2017. REUTERS/Carlos Barria

Sen. Tim Kaine (D-VA) has demanded the release of a secret memo that reveals the war powers President Donald Trump believes he legally possesses.

Kaine, Hillary Clinton's running mate and a member of the Armed Services and Foreign Relations Committees, sent a letter Thursday night to Secretary of State Rex Tillerson seeking the seven-page memo the administration has closely held for months, reported NBC News.

“The fact that there is a lengthy memo with a more detailed legal justification that has not been shared with Congress, or the American public, is unacceptable,” Kaine said in the letter, which the network obtained.

The Virginia Democrat has been asking the president to justify the U.S. bombing campaign he ordered last April in Syria after President Bashar al-Assad’s chemical attacks on civilians there.

The senator and other lawmakers are concerned Trump's order sidestepped congressional oversight of military action, and they're increasingly concerned about the administration's views on war powers as the White House escalates hostility toward North Korea.

“I am also concerned that this legal justification may now become precedent for additional executive unilateral military action, including this week’s U.S. airstrikes in Syria against pro-Assad forces or even an extremely risky ‘bloody nose’ strike against North Korea,” Kaine wrote.