The 5th Guards Tank Army fought in the East Prussian offensive as part of the 2nd Belorussian Front and the 3rd Belorussian Front. Its units entered combat in the sector of the German lines that the 48th Army had broken through on 17 January 1945 and by the end of the day had reached the Mława fortifications. By the morning of 19 January the army had defeated the garrison of the latter and developing the advance on Elbing reached the Frisches Haff by 25 January, cutting off the communications of Army Group Centre. In late January and February, the army repulsed German counterattacks attempting to push back the Soviet troops from the coast and restore land communications. From March 1945 to the end of the war Sinenko commanded the 5th Guards Tank Army. In early April, in conjunction with the 98th Rifle Corps and 1st Polish Tank Brigade, the army fought in fierce fighting to eliminate German forces in the Vistula Spit, where it remained until the end of the war.