The statement below justifies an international action

"The issue is the future of Southeast Asia as a whole. A threat to any nation in that region is a threat to all, and a threat to us."
-President Lyndon Johnson in his Message to Congress (August 5, 1964)

Which international action is President Johnson justifying with this speech?

Question 3 options:

Using sanctions against a country


Sending humanitarian aid to a country


Using nuclear weapons to end a war


Sending troops to stabilize a region