There is a loss of perspective and faith that came with the retirement of those who actually made America great.
What is mostly remarkable and this goes back to the 2nd Bush Presidency is the lack of informed, strategic decision making over the last two decades. Foreign policy is increasingly driven by internal and political considerations and ideas about how the world should operate rather than what specialists at the dept. of State, CIA and Pentagon think. Trump’s complete disconnect from his intelligence services is more than just a consequences of his lack of education and understanding.
Post 9/11 the Afghanistan invasion was inevitable but the Iraq one an unforced error. Repeated dithering on Iran, China and Israel also shows more the effects of a political agenda than of one driven by rational analysis, values and longer term interest.
Each new president thinks it is only the fault of his predecessor that determines results rather than the difficult to alter facts on the ground. All presidents think they can fix ties with Russia but then find out that Russia also has a say in the matter. Equally so relations with Iran, China and North Korea do not change on the whim of the current commander in chief no matter how intelligent (or not).
Where Obama stranded in eloquence and overanalysis, Trump’s foreign policy at least shows a willingness to try something. Trying to engage North Korea was a gamble perhaps worth the risk, but the inalterable fact remains that NK needs an enemy to justify its internal policies. Equally so Iran needs the US to be an enemy to justify spending and expansionism. Trump’s sanctions seem to be far more effective than previous attempts to appease and engage. Iran’s great success at establishing very strong leverage over Lebanon, Syria, Yemen, Gaza and Iraq only now seem to grind to a halt as the money to keep it lubricated is drying up thanks to these US sanctions. Obama and the EU turned a blind eye to Iran’s imperialism by thinking it could be decoupled from the nuclear deal and would somehow not be funded by new oil exports. Iran could advance unopposedly and the area was stubbornly neglected and handed over to Iran and Russia while the stakes only grew and grow higher.
Foreign relations with Russia are complex, Ukraine never received javelins anti tank missiles from Obama but did from Trump in 2017 and now again last month. Javelins are highly effective anti tank missiles and are credited with stabilizing the front. But other than that lack of effective containment of and strategy versus Russia is another post 9/11 blindness to the long term geopolitical interests of the US.