Attachment theory's secure/insecure classifications were developed and normed on a Western, mostly American middle-class sample, and the social milieux and caregiving arrangements the theory assumes vary widely across cultures, so it remains disputed whether the same classifications and their developmental meaning transfer to societies with different childrearing practices.
What would resolve this Attachment measures independently developed and validated within non-Western caregiving contexts, compared against the Strange Situation's own classifications and outcomes.
OpenWikipedia: Attachment Theory