a defensive attitude in which others are seen as hostile or potentially hostile
As performance deteriorates, they can easily become isolated, adopting a bunker mentalitythat makes matters worse.
They accuse him of having a bunker mentality.
bunker mentality in American English
an attitude or state of mind characterized by extreme suspiciousness and defensiveness and by a feeling of being under attack by a hostileopposition while being confined as if in a fortified bunker