To define our terms in the most basic way, I'm not sure that the UK was "undermined" by the USA in the post-war period. What we see during and after the war are differing - but sometimes complimentary - visions of the post-war world order.

The August 1941 Atlantic Charter was drafted by US and UK officials while the United States was still officially neutral in the war. It became a touchstone for the allied powers (including - to a certain extent and with a lot of caveats - the Soviet Union). It contained many similarities to Woodrow Wilson's Versailles-era 'fourteen points', including free trade, national self-determination, global cooperation for peace, disarmament, and a denunciation of the use of force in international affairs. It also included the rights of peoples to determine the fates of their own territories and the right of nations to free, democratic government of their own choice. Now, Winston Churchill in the UK and Charles De Gaulle representing France were quite keen to limit the charter's applicability in order to protect their imperial possessions (or in the case of France, to hopefully re-acquire their possessions after the war was concluded). Unlike Woodrow Wilson, Franklin D. Roosevelt was avowedly anti-imperialist, and was even at this stage deeply concerned that a failure to dismantle the old imperial-colonial structures would provoke a significant threat to post-war world peace (Luthi's book noted below, pages 20-21, has a very succinct but excellent section on the above).

From the Atlantic Charter there emerged in 1944 the Bretton Woods system, the global economic system that would survive until the 1970s. In brief, it would:Tie national currencies to the dollar, which would in turn be convertible into gold at fixed rates; create the International Monetary Fund and the World Bank, which would go on to become hugely powerful instruments of international economic policy, particularly in those parts of the world that were decolonising.

Right, so what does all this mean? Even as the war is continuing, there are already significant disagreements, disagreements which persist into the post-war period. Even Clement Atlee's Labour government that's in power from 1945 to 1951 is not exactly foresquare behind full-throated decolonisation. Indeed, there's a lot of work going on to enhance informal British imperial control in the Middle East, for example, through institutions such as the Arab League (which is a whole other ballgame and worthy of an answer of its own. Again, Luthi has an entire chapter devoted to this. It's really very good).

On the atomic side of things, we have the US Atomic Energy Act of 1946 (sometimes referred to as the McMahon Act after its prime sponsor, Senator Brien McMahon) and the involvement of congressional figures outside of the Truman administration in all of this. The AEA46 must be placed within the context of the emerging Cold War and the reinvigoration of domestic US anti-communism (and, tangentially to this discussion, the debate within government about who gets to control atomic power - civilians or the military? This was actually the main thrust of the debate surrounding the act, at least until the early 1946 revelations about Soviet penetration of the Manhattan Project). At this point, the British scientific establishment looked a little on the leaky side, as it turned out that the British physicist Alan Nunn May had been one of those supplying information to Moscow. The AEA46 therefore has an explicable dimension: a terrifying new weapon, and rapidly changing world, the threat of subversion, and the issues posed by the wider dissemination of information. Of course, a single paragraph can hardly hope to cover the complexity and enormity of the period or of the Act, but it wasn't quite a case of London simply being screwed over by Washington.

However, at the war's end the Truman administration finds itself in a position of such military and economic preponderance the like of which had never been seen before. The 1948 Marshall Plan (or European Recovery Plan, if you want to be formal about it) is a vast program of economic aid to assist Western Europe's recovery (it's also offered to Eastern Europe, but Stalin says "Nyet!"). And who is the biggest beneficiary of this dollar largesse? Why, it's the UK! The Marshall Plan was not solely responsible for European recovery (recovery was already taking place) BUT it does have important impacts in different national contexts.

Finally for this post, the US and UK working together is core to the creation of the North Atlantic Treaty Organisation (NATO). As I noted elsewhere a few weeks ago, Timothy Sayle's recent book Enduring Alliance: A History of NATO and the Postwar Global Order (which is very good, by the way), he argues that - certainly in the early days - NATO's primary mission, was not military containment of the USSR (i.e.: preventing an invasion into Western Europe), but to resist Soviet political blackmail over issues such as Germany, something that Washington and London were jointly concerned about. Moreover, Sayle contends that NATO (at this early stage) was as much a tool to reassure domestic audiences in Europe (including the UK) as it was a means of resisting perceived Soviet adventurism. Finally, it also existed to provide a framework through which a rebuilt West Germany could be safely further integrated into Western politico-military structures without causing undue alarm amongst those populations who had so recently experienced the events of 1939-45 (the UK being key here).

There is so much more that can be said about the 1941-49 period, and this is only really skimming the surface of the surface. I've got other stuff to do just now, but will carry on with a post about the 1950-56 period when I can.

Hope this helps.

Malcolm

Crucial sources for the above include:

Frank Costigliola, Roosevelt's Lost Alliances: How Personal Politics Helped Start the Cold War (Princeton: Princeton University Press, 2012)

Campbell Craig and Sergey Radchenko, The Atomic Bomb and the Origins of the Cold War (New Haven, CT: Yale University Press, 2008)

Lorenz Luthi, Cold Wars: Asia, the Middle East, Europe (Cambridge: Cambridge University Press, 2020)

David Reynolds, From World War to Cold War: Churchill, Roosevelt, and the International History of the 1940s (Oxford: Oxford University Press, 2006)

Timothy A. Sayle, Enduring Alliance: A History of NATO and the Postwar Global Order (Ithaca: Cornell University Press, 2019)

Susanna Schrafstetter, ‘“Loquacious...and pointless as ever?” Britain, the United States and the United Nations negotiations on international control of nuclear energy 1945–48’, Contemporary British History 16 (2002), 87–108

Mark Trachtenberg, A Constructed Peace: The Making of the European Settlement 1945–1963 (Princeton: Princeton University Press, 1999)

Could you be more specific about what you would like to know? Are you thinking of the Suez Crisis specifically?

The US & the UK had their differences in the early Cold War but I do not think it is fair to say that the USA undermined the UK in a general sense.