USA wanted to add extra fortification to Panama Canal defence according to the Weekly Intelligence Summary No. 9 dated 5 March 1921

An item reported that the US government asked in December 1920 the Panamanian government permission to include a part of an unnamed island in the region of Bahia de las Minas, east of Colon in the Canal Zone. The fortification was needed for the defence of the Panama Canal. Local US officials however already occupied the island despite there was no permission with as result that the relations between both governments were disturbed.

Source

The National Archives, Kew Gardens, England for the week ending 5-3-1921, CAB-24-120-88