Answer:
Step-by-step explanation:
Under international law a neutral country may not assist a belligerent power in any way that includes the trade in arms and munitions
Therefore once war broke out the US should not have permitted arms sales to any of the allied nations, however the Neutrality Act of 1939 modified the meaning a "neutrality" significantly in that it permitted the sale of war materials on the condition that they were paid for in cash not credit and that the belligerent power transported the materials themselves, however this clause was not open to all Belligerents
This was later amended to remove the "cash " clause and credit was extended and later still costs were offset by the leasing of bases overseas
After the fall of France the US also undertook shipping protection far beyond the limits of its territorial waters in an attempt the limit the impact of German Submarine Warfare and US ships were permitted to open fire if needed.
All of which offered help to the UK whilst not technically bringing the US into the war but any real pretence of neutrality were dropped