What action by congress allowed president johnson to expand the war in vietnam? why? what were the results?

During the Vietnam war, congress gave LBJ the unprecedented power of sending troops without declaring war. This allowed him to send US troops to Vietnam to support the war effort without getting completely involved in an all out war. After the war, Congress realized it should limit the president's power and they signed the war powers act that restricted the president's power to send troops to foreign countries. If the results of the war were different (if we had succeeded instead of failed) Congress may not have been so strict about signing the war powers act. Hope this helps, let me know if you need me to clarify or if you have more questions.