They come from all walks of life — Ukrainian actors, plumbers or IT professionals — and from all political persuasions. But one thing unites them, and that’s the defense of their country from a Russian invasion.

Thousands gather on weekends to learn military tactics and skills, and Fox News connected with some who say they are prepared for whatever comes their way.

"I remember the Russian military (from its) regular artillery and mortar attacks, including on civilian infrastructure and civilian homes," said Evgeny Leshan, a 46-year-old investigative journalist originally from the Crimea region. 

Following Russia’s annexation of the Crimean Peninsula in 2014, armed Russian separatists — alleged by Western countries to be backed by Moscow with troops and weaponry, something Moscow denied — took over predominantly Russian-speaking areas of eastern Ukraine.  

Leshan has firsthand experience fighting the Russian military and separatists. In 2014, he was an infantry fighting vehicle weapons operator in the Donbas region. 

"At the cemetery in the village of Granitne, near which we fought, there are graves of civilians who died due to Russian artillery shelling," Leshan said. "Actually, this is the essence of Russian expansion. Russians call themselves "saviors," but civilians are hostages or expendable material for them," he said. 

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Yet, for Leshan, it’s very important to be ready for any potential invasion, and that is why he and thousands of others are part of what is known as the Territorial Defense Force, a type of national guard he said "is needed so that the enemy of Ukraine does not feel safe anywhere …Wherever our enemy goes, wherever he appears, our guns will meet him everywhere." 

Leshan says things are much better organized, unlike in 2014.

"We saw in 2014 how small groups of Russian saboteurs, with the support of local provocateurs, took control of cities in the Donbas," Leshan recalled. "This was because there was no active local armed force to protect the cities. Now this force will be in every region, in every district, in every city of Ukraine.

"We will protect critical infrastructure, city security from sabotage groups and pro-Russian forces, and we will also meet enemy regular forces and take the fight to enable the army to use reserves and hit the enemy. Territorial defense is an opportunity for everyone to take part in the defense of their land." 

Leshan added that American support is vital. 

"I'm sure Americans understand very well how important a free Ukraine is. It is important not only for the Ukrainian people, but also for the whole of Europe, and for the whole world," Leshan said. 

"If Ukraine falls, it will be a tragedy for the Ukrainian people, and the balance in the world will also change in favor of the Russian archaic autocracy, and this is terrible, believe me. But I know that the Americans understand this. The volume of American military assistance is unprecedented, and the diplomatic support of Ukraine from the United States is also very large. 

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Observers say the civilian military units will play an important role against any Russian invasion with upwards of 130,000 Ukrainian volunteers to call upon from the pool of reserve forces. 

"The war with the Russian Federation has been going on for eight years. We live in this state all the time" says Illia Rykov, a 50-year-old businessman who is part of the volunteer forces. "Almost every day we receive news about the injuries or deaths of our soldiers in the Donbas." 

Rykov told Fox Digital he realized he had to do his part to help. 

"I decided that not only our army could help stop the aggressor, but also citizens like me. I am not a military man, but I was ready to learn how to defend my family and country," said Rykov.

Rykov joined the NGO (nongovernmental organization) Ukrainian Legion In 2016, describing it as "a civilian organization that has taken up training citizens in basic military skills. In 2017, I joined the territorial defense of the city of Kyiv. Today, for the sixth year in a row, I have been going through military training almost weekly on weekends." 

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Rykov said he is very grateful for the support the U.S. has given Ukraine over the years. 

"I want to thank the USA for the real help they have been providing to our country all these years," Rykov said. "This is very important and valuable for us.

"We are ready to defend our country and our values, our desire for democracy and freedom. We are at war with the Russian Federation, which has one of the strongest armies in the world, whose state policy denies the very existence of the Ukrainian nation and Ukraine as a state. We believe in continued support from the U.S. government and the American people in our fight against the aggressor." 

Oleksii Sannikov works in Ukraine’s IT industry by day. A father to a teenager, Sannikov runs an NGO called the Ukrainian Legion, whose goal is to "train ordinary Ukrainians in the art of civilian defense," he says. 

Oleksi Sannikov

Oleksi Sannikov (Fox News)

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"Our NGO prepares civilians to act in some critical situations — and war it is just one case," Sannikov said. "After our training, people can recognize if they want to build a military career."

He says the organization is a training platform for civilians, but says it may soon be officially recognized. 

"According to new regulations, we can become a combat unit and an official part of forces of territory defense," he explained. 

He said his organization has about 450 members and has trained over 4000 civilians. He says he wants the American public to understand Ukrainians want to live separated from Russia.

"Not every brother is a good brother, you know," Sannikov said. "We can live in peace, but they must forget about their desire to enslave us again." He said he understood how difficut it will be "to fight with Russia troops, but if (the) USA will help us with some lethal weapon(s), and if you will close a sky, I suppose we will handle this situation." 

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Rykov and his band of brothers and sisters are far from being weekend warriors. He makes sure to point out that they are trained by former and current military personnel and says that several times each year they train with Ukrainian army units to gain additional skills and knowledge.  

"As part of our training, we study combined arms disciplines, tactical medicine, topography and engineering training," Rykov explained. "In addition to obtaining theoretical knowledge, we constantly work out these disciplines in practice during our trainings. 

"In our ranks, there are people who fought in the Donbas as well as ordinary citizens of different ages, gender and professions. This is not a commercial initiative. We are engaged in (this) voluntarily, without receiving remuneration." 

Rykov and his colleagues are ready to fend off what they see as the Russia aggressor if an invasion comes. 

"If there is a full-scale invasion (by) the Russian Federation, I am ready to take up arms and go to defend my city and country," Rykov said. "My family is here, my children were born here, my parents and friends live here. I have someone to protect." 

The Associated Press contributed to this report.

Ben Evansky reports for Fox News on the United Nations and international affairs. He can be followed @BenEvansky.