T. A. Gardner
Thread Killer
Blah, blah, blah. Not a fucking word answering the question. The fact is obvious: It's not in the Constitution.
https://www.law.cornell.edu/wex/war_powers
https://history.house.gov/Institution/Origins-Development/War-Powers/
As for undeclared wars, the US has fought many of those too...
https://history.house.gov/Institution/Origins-Development/War-Powers/
The US obviously can as a sovereign nation fight wars with other nations or against specific groups whether you like it or not.
Now, I will say that LBJ used a blatant lie (the Gulf of Tonkin incident) to get America into Vietnam.