For some value of "defense". Back when the US DOD was called Department of War, it had (at various times) flagged boots on the ground in china[1], north korea, and russia[2].
[1] In the lost opportunities department, General Wedemeyer on "who lost china?" (emphasis mine):
> "If Uncle Sugar, Russia, and Britain united strongly in their endeavor to bring about a coalition of these two political parties [the Kuomintang and the Chinese Communist Party] in China by coercing both sides to make realistic concessions, serious post-war disturbance may be averted and timely effective military employment of all Chinese may be obtained against the Japanese. I use the term coercion advisedly because it is my conviction that continued appeals to both sides couched in polite diplomatic terms will not accomplish unification."
[2] thanks to burnaway's excellent search fu: https://news.ycombinator.com/item?id=24490540 I learned US propaganda in 1914-1918 had not only been officially going to russia, but also the then-white entities (where American Expeditionary Forces were operating) archangel and siberia.
Iran, on the other hand, was a brit show up until Ajax (1953) or so: https://en.wikipedia.org/wiki/Iran–United_Kingdom_relations#... The US would not formally take the baton before ending Suez (1957).
[1] In the lost opportunities department, General Wedemeyer on "who lost china?" (emphasis mine):
> "If Uncle Sugar, Russia, and Britain united strongly in their endeavor to bring about a coalition of these two political parties [the Kuomintang and the Chinese Communist Party] in China by coercing both sides to make realistic concessions, serious post-war disturbance may be averted and timely effective military employment of all Chinese may be obtained against the Japanese. I use the term coercion advisedly because it is my conviction that continued appeals to both sides couched in polite diplomatic terms will not accomplish unification."
https://en.wikipedia.org/wiki/Albert_Coady_Wedemeyer#China-B...
[2] thanks to burnaway's excellent search fu: https://news.ycombinator.com/item?id=24490540 I learned US propaganda in 1914-1918 had not only been officially going to russia, but also the then-white entities (where American Expeditionary Forces were operating) archangel and siberia.