What is the rules-based order?

Is the liberal international rules-based order – that has underpinned international relations for the past 80 years - about to collapse. The United States once its greatest champion is withdrawing funding from hundreds of international organisations, and at the same time unending the global economy by imposing of tariffs across the board. What might this mean for global security, and the global economy and can we blame Donald Trump and his wrecking ball or are there deeper forces at play?