Presidential War Powers

By CHARLIE SAVAGE
APRIL 7, 2017

... The United Nations Charter, a treaty the United States has ratified, recognizes two justifications for using force on another country’s soil without its consent: the permission of the Security Council or a self-defense claim. In the case of Syria, the United Nations did not approve the strike, and the Defense Department justified it as “intended to deter the regime from using chemical weapons again,” which is not self-defense ...

... Tillerson, in a briefing with reporters, invoked Syria’s violation of the Chemical Weapons Convention and a related Security Council resolution from 2013 ...

However .. the resolution .. did not directly authorize force ...

... Most legal scholars agree that the founders wanted Congress to decide whether to go to war, except when the country is under an attack. But presidents of both parties have a long history of carrying out military operations without authorization from Congress, especially since the end of World War II, when the United States maintained a large standing army instead of demobilizing ...

https://www.nytimes.com/2017/04/07/us/politics/military-force-presidential-power.html