Answer:
they are threatening the US to a. not join the allies and b. join the axis
Explanation:
Germany was a powerful country. There was a large amount of fear that the US would join the war, and the Germans tried everything that they could to stop them, even going to threatening the US government if they voiced their support for the British, who they were trying to cut off from the trade routes and starve. By doing this, they were trying to persuade the US government to leave Britian, let the British be surroudned and cut off from trade, and join the Axis (german) side.