In 1957, he married  a high school teacher having met her when he visited his parents back home. A year later, he graduated from the Higher Officer Classes in Leningrad, and was appointed commander of the first nuclear submarine in the Pacific Fleet. 

In 1965, he graduated from the Naval Academy in Leningrad and finally, in 1971, from the Academy of the General Staff in Moscow. Then, on the 6th May, 1972, he was promoted to Rear Admiral whilst he was in command of the 10th Submarine Division. 

In September 1974, he was placed in command of the 6th Submarine Squadron, and remained in this office until November 1978, shortly after he had been promoted to Vice Admiral. In October 1979, he was assigned command over the 4th Submarine Flotilla. 

In 1974, he participated in an operation to track nuclear submarines from the 15th US Squadron, as part of a search and strike group. Belashev considered it his duty to study American combat activities, but he didn't do this from an office. Instead, he did it directly at the combat training grounds of a potential enemy, which meant he ended up on the ship of Captain N. Makarchuk, which was on combat duty in the Philippine Sea, where he spent a vast amount of time in the conning tower. The experience he gained from this particular situation helped him to make significant proposals which were later used to improve the tactics of the Pacific Fleet. 

He was constantly at sea, which meant that he had no free time, and was considered to be able to sleep standing up on a tram whenever his family was with him. He was known as a kind, decent and educated person, reflected by his knowledge of Pushkin, which he could navigate by heart. He was known to be very strong willed, reflected by his joining his classmates to completely quit smoking at the age of 34 and, by New Years' Eve when everybody was lighting cigarettes, he did not join in. He enjoyed being in shape and was known to run around with his dog in the morning. 

He also loved fishing, something he could rarely find time to do because of his busy schedule. He claimed that, when he retired, he would buy a house in the village, get two huskies, and he would go hunting and fishing. After his death, his family found many unused fishing accessories in his home.

In February 1981, he was originally on holiday. However, he flew out to attend the meeting. The night of the 6th, his daughter called to say that she would be at home in the morning, however, on the 7th of February, they received the terrible news that he had been killed.