Words mean different things to different people. Personally I have never heard "backyard" as in "in my backyard" used that way. A slang dictionary yields this:
>An area nearby to a country or other jurisidiction's legal boundaries, particularly an area in which the country feels it has an interest. https://www.yourdictionary.com/backyard
Which seems spot on, I swear I didn't just write that myself. The WSJ even went so far as to call Equatorial Guinea (in West Africa) part of America's backyard: https://archive.fo/8UjYC
"In my own backyard" would connote what you are saying, but there's an extra word "own" there.
That's fine, but the implied sentiment was that if there is trouble in Europe's 'backyard' that we're on our own, loud and clear. Isolationism worked so well against mad dictators the last time we tried it, I'm sure this time around it will all be peachy.
>An area nearby to a country or other jurisidiction's legal boundaries, particularly an area in which the country feels it has an interest. https://www.yourdictionary.com/backyard
Which seems spot on, I swear I didn't just write that myself. The WSJ even went so far as to call Equatorial Guinea (in West Africa) part of America's backyard: https://archive.fo/8UjYC
"In my own backyard" would connote what you are saying, but there's an extra word "own" there.