depends which war your talking about
AUSTRIAHUNGARY
anyone could decalre war
3 September 1939
There was no way Serbia could avoid Yugoslav war, because if there was Serbia would have done it...
Serbia was in WWI because Austria-Hungary declared war on them.
Serbia Serbia
When Russia found out that Austria-Hungary was declaring war on Serbia, they came into alliance with Serbia for several reasons.
The 1st country to declare war on Serbia was Austria-Hungary.
The war between Serbia and Kosovo was going on. The war started because Serbia wanted more territory from Kosovo.
Austria-hungary attacked Serbia
Russia