"Migrant crisis is the
intense difficulty, trouble, or danger situation in the receiving state (destination country) due to the movements of large groups of [economic]
immigrants (
displaced people,
refugee or
asylum seeker)" invading without invitation.
[Every population, including immigrant populations, comprises a majority whose contributions are benign or beneficial, and a minority who inadvertently elicit or deliberately invoke civil distress. Of late, adversarial states view spontaneous migration as an opportunity to insert criminals, spies, terrorists, and state-sponsored troublemakers into unsuspecting host populations. Despite being a minority of arrivals, these individuals cause disproportionate trouble.
When the immigrants are predominantly young males,
economic migration is the likeliest stimulus for most who, honestly or dishonestly, claim "asylum". Unfortunately, young males are the likeliest to cause social disruption, particularly since some/many unattached males continue to hold and manifest unacceptable attitudes and behaviors towards the host culture's women and female children [e.g.
Rotherham child sexual exploitation scandal].
In many Western nations, these young males also continue to exhibit the learned violence endemic in their nations of origin -- both an inducement to emigrate, and a cause of cultural aversion in host populations. The negative feelings elicited by antisocial behavior further contribute to the failure of individuals from markedly different cultures to assimilate satisfactorily.