Russia intending to snet seaplanes to Archangelsk according to the Weekly appreciation of matters of naval interest No.13 week ended 15 March 1919

An item reported that although there was no new action at Archangelsk, Russia preparations were made to sent a squadron of 6 seaplanes through the ice to Archangelsk as soon as possible and 12 special miners were sent to mine the river if needed.

Source

The National Archives, Kew Gardens, England CAB-23-76-10