Hmmm.... America's soft power decline has been happening since the 90's. For example. Most of the world is staunchly against Islamic Imperialism that is plaguing the world in especially the Middle East and South Asia, but previous administrations continuously undermined that narrative. For example this heavily alienated India, which is why India has continued its deep alliance with Russia. Because Russia also understands the culture, religion, and geopolitics of the region. Perhaps America is so geographically divorced from that region that American politicians just don't get it, but that is reason for our decline.

Another soft power plunder was the whole Arab Springs, and the Middle East in general. Another was the release and making apparent the fact of US spy capabilities rather then it remaining as fringe conspiracy theories. That really tarnished the USA's global image. Another blunder is the decline of American manufacturing and machining. Unbeknownst to many people America had a genuine tradition of tradesmen, and people with decades of deep knowledge that produced high quality products and specialized tools. That declined and those tradesmen were out of a job. Now a few decades later it's ever so harder to retrain and regain that deep industrial knowledge.

We can go one about American blunders all day long actually in all sorts of fields, and going back decades, and fundamentally it boils down to the lack of leadership and global vision. Perhaps America never had it in the first place and only "won" due to historic circumstance. But the best possible route for America, as I see it, especially in light of the absolute failure in recognizing terrorism, Radical Islam, and the Middle East is to pursue isolationist policies to at the very not squander what wealth America already has and safe guard America for the next few decades until another more opportune moment is there for America on the world stage. If there is one...