belligerent

Short definition from Wiktionary

Adjective

1. 1
   Engaged in warfare, warring.
2. 2
   Eager to go to war, warlike.
3. 3
   Of or pertaining to war.
4. 4
   Aggressively hostile, eager to fight.
5. 5
   Acting violently towards others.
6. 6
   Uncooperative.

Noun

1. 1
   A state or other armed participant in warfare