MPs have been warned that the White House is stepping back from because it "could not do a war on two fronts" and fears a direct conflict with China - a "true peer" of the United States.
Dr Rowan Allport from The Human Security Centre told the UK's Defence Select Committee: "China represents a far greater challenge to the US than Nazi Germany, the Imperial Japan or the Soviet Union. They are a true peer.
"The US is not saying that Europe needs to step up to be difficult, or because of MAGA [Make America Great Again] or anything like that. It is doing it because it could not do a war on two fronts."

The Trump administration has repeatedly told European NATO partners that it would no longer prop up defence on the continent and that it was reorienting its defence posture towards Beijing.
During the Munich Security Conference earlier this year, US vice-president : "President Trump has made abundantly clear, he believes that our European friends must play a bigger role in the future of this continent
"We think it's an important part of being in a shared alliance together that the Europeans step up while America focuses on areas of the world that are in great danger."
Meanwhile, in March embattled US Defense Secretary Pete Hegseth realigned the superpower's defence priorities, "assuming risk" in Europe in order to reallocate resources to deter China from taking Taiwan.
"China is the Department's sole pacing threat, and denial of a Chinese fait accompli seizure of Taiwan - while simultaneously defending the U.S. homeland is the Department's sole pacing scenario," Hegseth wrote in a secret guidance, according to .
This comes as the UK has begun preparing for a strike from Russia. According to , officials have been asked to update 20-year-old contingency plans that would put the country on a war footing. This comes after threats of attack from the Kremlin, following the UK's plan to lead a coalition of the willing to keep the peace in Ukraine in the event of an agreement to end the war.
The classified dossier sets out how the Government would respond to a declaration of war from a foreign state, including holding the Cabinet and Royal Family in bunkers, public service broadcasts and the stockpiling of resources.
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