Danubian-Romanian War (19 October 1929 - 23 December 1930) - was a military conflict between newly established communist Danubian Republic and Kingdom of Romania. It was part of Danubian campaign against separatist movements within former Austro-Hungarian Empire.
Bela Kun saw the war as necessary not only to consolidate power in former Austria-Hungary but also to spread revolution abroad. Romania on the other side was interested in annexation of Transylvania, Banat and Bukovina inhabited mostly by Romanians.
The war ended on 23 December 1930 with Peace of Belgrade. It gave Danubian Republic control over Carpathian passes, but failed to spread revolution to Romania.