Trump may be mentally unstable, but the US military is not. Lots of bright and talented people there.
I always admire, grudgingly , how the US skillfully achieves her strategic economic gains through propaganda and warfare, all the while under a just and righteous banner. the Free Trade Agreement among China , Japan and SK was disrupted by bringing in the Diaoyu Dao dispute, Saddam Hussein and Gaddafi toppled for trying to switch to petroEuro, and now Iran threatened for trying the same.
And I can't help but feel that the US Navy is now in SCS, partly to scuttle the impending signing of the RCEP among ASEANS, China, Japan and SK. I heard that the Chinese RMB will be used instead of the US dollars once RCEP is signed, but I don't know if it is true.
I disagree with your assessment.
U.S Foreign Policy and Strategic Decision Making has been an unmitigated disaster in the past two decades. At the turn of the century, the United State reigned supreme as the undisputed hegemon of the international system. Yet it has squandered its position in quick fashion. I will list three major strategic catastrophes here.
1) The War on Terror and The Invasion of Afghanistan and Iraq. The vast cost of the wars depleted U.S treasure, resulting in nothing except the creation of two failed state with ongoing conflicts 20 years and counting. By removing Sadaam from power, U.S unwittingly handed regional influence back to Iran on a silver platter.
The subsequent intervention in Syria and Libya ended in utter failure once again. The resulting necessity to deal with ISIS sapped any momentum in "Pivot to Asia" and and further delayed strategic focus back towards Great Power Competition.
2) Three rounds of Eastward NATO expansions pushed U.S Russia relation beyond the point of no return, directly resulting in Russian/Georgia War and Russian Annexation of Crimea. And thus, Russia is lost as a potential balancer to a rising China.
3) The Great Recession at home and the collapse of the Washington Consensus abroad. In the ten years following the Great Recession marked a reversal of economic fortune more rapid than any other points in recorded history. In 2008, the GDP of PRC by PPP was a mere 60% of U.S GDP. By 2018, It is 120%. Total industrial output, a key attribute of a nation's capacity for war, followed the same trend.
These, among many other missteps, has made the U.S far weaker and far less ready for the unavoidable resumption of Great Power Competition. The United States has squandered its moment of Unipolarity, to no avail.