The return of Dutch authorities was rejected by a majority of the native population, resulting in various regional armed conflicts between the Royal Netherlands East Indies Army and Indonesian nationalist forces.

This later caused tensions between royals and people of Kutai, some of whom formed the Panitia Aksi Anti Swapraja (Committee for Anti-Royalty Action) and actively opposed the Dutch puppet state.

[1] In South Kalimantan, armed opposition was led by Hasan Basry in Meratus Mountains, with smaller conflicts occurring in Kotabaru and Tanah Laut.

Anti-royalty and anti-Dutch sentiment were thought to be driven by influence of Communist Party of Indonesia in the region, which was exceptionally strong in South and East Kalimantan.

[15] The Indonesian Navy, which had been founded in 1946, also sent secret emissaries to establish communication with nationlists in Kalimantan, to give them support and to attempt to bring them under their command.

[citation needed] In October 1947, newly formed Indonesian Airforce (AURI) conducted its first ever airborne operation led by Tjilik Riwut in what today is Central Kalimantan using a Douglas DC-3 aircraft disguised as civilian plane.

[18] On 17 May 1949, Hasan Basry declared Kalimantan as integral part of Indonesian Republic and opposed any act to grant it independence from Indonesia.

The Dutch did not recognize the proclamation and made a military push to limit the actual reach of Basry's claim to establishing a new Indonesian territory on Kalimantan soil.

[1] Starting in the late summer, while the Dutch–Indonesian Round Table Conference was being negotiated in The Hague, Indonesian defense ministers Mohammad Hatta (replaced by Hamengkubuwono IX during the negotiations) sent a military force led by Major General Soehardjo to peacefully observe the state of affairs in Banjarmasin, where the Dutch KNIL forces were still mobilized.