The Hay-Pauncefote Treaty between the US and Great Britain dealt with this.
War of 1812
Lend-lease during WWII
The Panama Canal. There were two Hay-Pauncefote Treaties; the senate refused the first one because it limited US control of the canal. The second, signed in 1901, allowed the US all rights to build and manage the canal, which originally a US-British project.
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