Helicopters , battleships and minesweepers hunt for vessel . ` We do n't know what it is , '' but we `` are prepared to use anything necessary to bring the vessel to the surface if we need to , '' Swedish military spokeswoman Therese Fagerstedt told CNN on Tuesday . Emergency radio call picked up by Swedish military , report says . Radio transmissions sent to Russian enclave on Baltic Sea , report says . Comment:
Helicopters , battleships and minesweepers hunt for vessel . Emergency radio call picked up by Swedish military , report says . Radio transmissions sent to Russian enclave on Baltic Sea , report says . Comment: