Many of these countries carry yooge dollar-denominated debts, and are in turn strapped for dollars.
This forces them to turn to alternative sources of financing - particularly China.
Argentina in particular doesn't have Chinese military bases (though they do have a small U.S. military base in the SW) - but it does have a Chinese satellite tracking station in Patagonia.
And why?
Because in 2014, Argentina was forced to turn to China for a $10 billion currency swap when the country's credit was ruined by vulture fund lawsuits that literally stopped U.S. bondholders from receiving their checks by court order (the late Judge Greasa, with his million-dollar Montana ranch).
The Chinese even threw in a massive hydroelectric dam project - which was nixed by Macri in 2016, but now revived with this agreement (Macri, ironically, was forced to turn to China himself for another $8 billion when his debt bubble burst).
In return, that's what they asked for: the tracking station, which is still there - near the U.S. base, of course.
Were it not for the vulture fund credit blockade (which many in Argentina saw as being U.S.-sponsored), and Macri's $100 billion debt hangover a few years later, Argentina's relationship with China would be far more limited.
But now, they need their help.