What does Truman mean when saying, "The world is not static, and the status quo is not sacred"?

The world was changing due to World War II--this quote is from what is now referred to as the Truman Doctrine and sets containment as the method for foreign policy.

This quote refers to the changes in the power of the world and how the US now needs to step up in defending the UN Charter. The US can't isolate and must now ensure countries fighting for independence are supported.