What does Senator Kaine argue is Congress's proper role in the war against ISIS?

The Democratic senator by the state of Virginia, Timothy Kaine, crossed out of illegal the decision of Trump to attack Syria.

"Trump's decision to attack Syria without congressional approval is illegal." The Senator argues that President Trump's Administration is based on a war approval of 2001, after the attacks of September 11. It is based on the fact that it is not possible to continue in this way after 17 years, and therefore proposes that the Congress revoke the 2001 authorization and work on a new authorization if necessary.