'My call sign is 'Grandad.' The retirees who are frontline fighters for Ukraine against the Russian invaders

• Some volunteer fighters in Ukraine are considerably older than the average age of a typical soldier.
• 63-year-old Leonid Onyschenko, for example, is fighting for Ukraine near the city of Bakhmut.
• Ukraine is one of the "oldest" countries in the world, according to Amnesty International.

In Ukraine's bloody battles, there are retirees fighting side-by-side with their younger comrades.

While the classic image of a soldier in battle evokes a fit young person with a chiseled jawline, the diverse volunteer fighters in Ukraine defy this expectation. As Russia's invasion of Ukraine enters its second year, some soldiers putting their lives on the line for their country are graying, grandparents, and well-past retirement age.

Leonid Onyshchenko, 63, once a nuclear physicist, is now fighting the Russian military near the city of Bakhmut, according to a social media post by the Ukraine Territorial Defense Forces last week.

The Territorial Defense Forces (TDF) — a volunteer military reserve — said that Onyshchenko had been serving the country for nine years since Russia's invasion and illegal annexation of Crimea in 2014. The post includes a photo that appears to show the physicist-turned-fighter jumping down from an armored vehicle in military attire.

"Now we are completing what our grandfathers started 100 years ago. When it becomes difficult, I always tell the boys what kind of fighters they were," Onyshchenko said.

Onyshchenko added he is ready to fight "regardless of age, regardless of anything. Until we win, we will not lay down our arms," according to the Facebook post.

Similarly, another post shows two graying 59-year-old men named Mykola and Vasyl with their arms around each other. The two are "senior, literally and figuratively, soldier and sergeant" of 112th Territorial Defense Brigade in Kyiv, a TDF Twitter post said.

"Their 30-year friendship is stronger than the entire Russian army," the forces said.

—Ukraine Territorial Defense Forces (@TDF_UA) February 28, 2023

"As long as my health keeps me fit, I keep a machine gun with me"

At the beginning of the war last year, 100,000 Ukrainians volunteered to join the TDF, according to local news.

The average age of soldiers tends to skew young. In the United States, for example, the majority of active duty Armed Forces personnel in 2021 were under the age of 30, according to Statista data.

It is normal during wartime, however, for the age of those fighting to increase — particularly when there is conscription. Last February, Ukrainian President Volodymyr Zelenskyy declared — with certain exceptions — men aged 18 to 60 could not leave the country.

Even so, just days before Russia invaded Ukraine last year, Reuters reported that seniors on both sides were preparing to fight in the war — signing up to get basic weapons and first aid training. Many of the older volunteers the news outlet spoke to appeared eager to stay in eastern Ukraine at the time.

Another popular video on social media posted by Butusov Plus last month shows an interview soldier who is 71 with the callsign "Grandad." Working as a mortar operator in the Donetsk region, the interviewer on the YouTube channel covering the frontline in Ukraine asked the retired engineer how he is still able to fight.

Fighting as a volunteer for the Ukraine army for six years in some of the most intense battles in eastern Ukraine, he said this battle fitness could be down to a lifetime of playing sports and climbing mountains — though he admitted he remains a committed cigarette smoker.

"As long as my health keeps me fit, I keep a machine gun with me. Who will protect us? If not us, then who?" he added.

—Anton Gerashchenko (@Gerashchenko_en) February 3, 2023

Fathers and sons went off to war

Because the TDF is volunteer-based — but still a branch of the Armed Forces of Ukraine — the "citizen soldiers" are made up of a diverse group of Ukrainians with a wide range of ages and varying levels of experience. What unites them, according to a report by Esquire last year, is "a fierce love of their country."

"For older people to come back and volunteer to fight, it's much different from an 18-year-old that is just starting out," Mark Cancian, a senior advisor at the Center for Strategic and International Studies, told Insider.

To some extent, the senior age of certain volunteers "shows the depth of Ukrainian feeling to defend their country," he said.

On the other hand, Cancian added, an increased age of military volunteers to fight is very common during war, particularly in "situations where you have more fluid forces."

In Ukraine, there are several reported cases of fathers and sons joining the combat. The @NOELreports Twitter feed, dedicated to covering the war from a pro-Ukraine perspective, recently featured a 50-year-old soldier named Valera from Zakarpatska.

"Valera has been fighting since the first day of the invasion. His 27-year-old son was badly wounded near Kherson when a mortar landed nearby. Despite everything, Valera continues to fight. "All the way to the Urals, if we have to," said the Twitter feed

Russia drafted a senior with diabetes

On the other side of the conflict, Russia's military conscription was upped from men aged 18 to 27 to 30 years old in January to serve one year. However, following the mass mobilization of 300,000 last year meant the average age of mobilized soldiers in Russia is 35, according to The Atlantic.

Reports showed that Russia was drafting older people, including a 63-year-old man from the Volgograd region, the independent Russian news site The Insider reported. (The outlet has no relation to Insider.)

The man, identified only as Yermolaev, was suffering from second-degree diabetes and a brain condition known as cerebral ischemia, The Insider reported. Yermolaev had previously served in the army but was retired.

He was told by doctors that he was "fit to go to the front," The Insider reported.

Insider was unable to independently verify the accounts.

For the older men still able to serve in Ukraine's armed forces, their lives still appear to have a purpose, but for many of elderly people caught up in the worst European conflict since World War II the fighting has only bought misery and despair.

Reports by Human Rights Watch and Amnesty International have both found that older people in Ukraine — one of the "oldest" countries in the world, with one in four over 60 — have been significantly impacted by the conflict. Older people affected by the confront "intersecting challenges, from disability to poverty to age discrimination," putting them at "heightened risk," said Amnesty.