A siege mentality will do that.

Indeed, an Israeli academic one Daniel BarTal stated as much, #4 is a doozy: https://www.beyondintractability.org/essay/siege_mentality:

Siege beliefs have emotional and behavioral implications that can have serious consequences for the society, as well as for the international community.

1.

The threatened society with siege beliefs develops negative attitudes towards other societies, which may be accompanied with feelings of xenophobia and chauvinism.

2.

The society becomes extremely sensitive to any information and cues transmitted by other societies that may indicate negative intentions.

This developed sensitivity is based on lack of trust and suspicion that society members feel toward other societies which, in their view, have negative intentions.

3.

The society develops internal mechanisms to cope with the threat by increasing pressure among society members towards conformity, unity and mobilization.

This pressure can take various forms, like calls for unity, calls for patching-up or concealment of disagreement within the group, as well as threatening (and carrying out) negative sanctions against those who disagree within the group.

4.

Finally, a society may take a course of action without consideration of international behavioral codes.

A society that feels endangered may decide that its need to survive is so paramount that all means can be used.

As a result, it may decide to take a course of action considered extreme and unacceptable by the international community.

In this situation, society members may disregard any unfavorable reactions from these other groups, which they consider as their adversaries anyway.

Another article:

https://www.sciencedirect.com/science/article/abs/pii/014717679290052V