I have said more than once: every man - and not only a man - should be able to at least handle weapons," Lukashenko said at the meeting of his Security Council.
Lukashenko, who allowed Russia to use Belarus to send troops into Ukraine a year ago, has often said his army would fight only if Belarus was attacked.
"In case of an act of aggression, the response will be fast, harsh and appropriate," Lukashenko said on Monday.
Defence Minister Viktor Khrenin said the territorial defence force will have 100,000-150,000 volunteers, or more if needed.
The country's professional army has about 48,000 troops and some 12,000 state border troops, according to the 2022 International Institute for Strategic Studies' Military Balance.