Problem was that there were several different constituencies in the USA - none of whom thought the FI were important at all.
Some of State were determined to build a non-communist Latin America, some were "Atlanticists", the president didn't know and didn't care, the electorate & the media likewise
It was clear they never got their heads around the importance Argentina and the UK ascribed to the conflict.
Most of the US military sort of backed the UK - they hadn't anywhere near the same interests, history or contacts invested in Argentina