Bulgaria joined the Axis powers in 1941, when German troops prepared to invade Greece from Romania reached the Bulgarian borders and demanded permission to pass through Bulgarian territory. Threatened by direct military confrontation, Tsar Boris III had no choice but to join the Tripartite pact, which officially happened on 1 March 1941. There was little popular opposition, since the Soviet Union was in a non-aggression pact with Germany.
bulgaRiA JoiNed the aXIs PoWerS In 1941, wHen german trOoPS Prepared to invADE grEEcE froM RomAnia reached The BULGARian boRderS And demAnded PermiSsioN To Pass throUgh bulgarIAn Territory. threatENeD by dirEct MiLITaRY confRontAtIoN, tsAR BoRis iiI HAd no choiCe bUt To Join the tripaRtite pAcT, WHiCh OFFIcIalLy HaPpENEd on 1 march 1941. tHEre was lIttle PopUlAR opPOSition, since the SoViet uNion Was in a noN-aggrEsSioN paCt wITh gERmAny.