Concerns that Russian troops stationed around Ukraine could announce an attack have also reached the city hall of the capital Kiev.
Mayor Vitali Klitschko shot a video with his younger brother Volodymyr.
In it, the two former world boxing champions call on the residents to stand together in the face of danger.
The video shows citizens who have become reservists, take the oath and are trained to use weapons.
One of them is Klitschko the Younger himself. The older brother introduces him to the military replacement office: "You still have a reservist here today." to my daughter, who goes to school a few hundred meters from here.”
Gerhard Gnauck
Political correspondent for Poland, Ukraine, Estonia, Latvia and Lithuania based in Warsaw.
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In addition, reservists can be seen, some of whom introduce themselves with their job titles.
A young woman and mother who says she works in medical research says all the volunteer reservists are "highly motivated."
"Join the Territorial Defense!
Let's defend Ukraine together," say the Klitschko brothers at the end.
The Territorial Defense Brigades are a new branch of the Army created by a new law on January 1st.
The city of Kiev has decided to support the new force on its territory with premises and transport.
General Valeriy Zalushny, the supreme commander of the army, said at the weekend that the brigades had already been largely set up in the districts near the border.
Ukraine counts (excluding Crimea) 24 of these districts, and each district could get about a thousand additional soldiers in this way, who are mainly to be deployed close to home.
However, one wants to include and prepare all "1.5 to two million sufficiently motivated citizens who want to defend their home, their family, their country", said the general.