This common propaganda method is when the speaker tries to convince you to accept their point of view or else we will miss out on something really good. The Band-Wagon technique is often used in the advertisement but more and more also transposed into populist speeches and claims of the political rhetoric.
"IF NOT NOW WHEN?" asks the imperative. In this propaganda, time is used to empower a message. Example: Seize the day, no time like the present, enough is enough, we must act now, will nobody think of the children?
"Of course the people don't want war. But after all, it's the leaders of the country who determine the policy, and it's always a simple matter to drag the people along whether it's a democracy, a fascist dictatorship, or a parliament, or a communist dictatorship. Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the pacifists for lack of patriotism, and exposing the country to greater danger."