The An-26 transport plane disappeared Monday afternoon. A search mission in eastern Ukraine's Luhansk region -- the site of fighting between the army and rebels -- is currently underway. There was no information given regarding how many people were aboard.
The incident came after military spokesman Oleksiy Dmytrashkivskyy confirmed on Ukrainian television the military delivered "five powerful air strikes on targets where militants and hardware were concentrated. Air strikes were delivered on targets near the Luhansk airfield; two strikes were made near Izvaryne and one near Lysychansk" -- both Luhansk region towns.
In the last three days, at least 19 soldiers died in a rocket attack near the border with Russia, rebels claimed they attacked an armed convoy near Luhansk airport, and Russia accused Ukraine of firing across the border in an incident in which one person was killed.
Germany and Russia have called for direct talks between the Kiev government and the separatists who seek independence for the eastern regions of Luhansk and Donetsk. The United States and the United Kingdom have emphasized Russia faces additional economic sanctions if it does not take a more active role in the peace process.
Notable deaths of 2014 [PHOTOS]