What is Niko's nationality in GTA 4?

Given his European origins, some GTA 4 players remain confused about Niko Bellic’s nationality.

Niko Bellic GTA 4 Characters, Bio & Voice Actor (GTA IV, TLaD & TBoGT)

10 Best Fictional Characters That Are Slavic – Slavorum

GRAND THEFT AUTO IV - Main Characters

Niko Bellic, GTA Wiki

Niko Bellic Fan Casting for GTA Protagonists in Live Action

Proof that GTA IV Niko is Serbian. : r/gaming

Niko Bellic, Rockstar Games Wiki

My favourite ever GTA quote (Niko Bellic) what's yours? : r/GTA

So what is the nationality of Niko? - GTA IV - GTAForums

An old Tweet but I thought it'd be interesting to share nonetheless. Niko's voice actor confirming that he's Serbian : r/GTAIV

Niko Bellic, Rockstar Games Wiki

Niko Bellic - Grand Theft Wiki, the GTA wiki