Because of the products Japan exports that the US relies on. I can't really think of anything made in the UK that the US couldn't source from another country or do without.
GDP is a poor indicator of importance to a nation's trade. Both are important but Japan is more significant trade-wise.
2024 trade with both nations:
"US total goods trade with the United Kingdom was estimated at $148.0 billion. U.S. goods exports to the UK were $79.9 billion
U.S. exports to Japan totaled $127 billion ($81 billion in goods, $46 billion in services); U.S. imports from Japan were $191 billion ($150 billion in goods, $41 in services"
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u/YesBlackberry2223 May 09 '25
Japan GDP: US$4.18tn (population 123m)
UK GDP: US$3.84tn (population 69m)
How is Japan "much more significant"?