As Russian forces advance on Kyiv, Ukraine’s capital, people all over the country are being urged by officials — and sometimes compelled by necessity — to fight back in whatever ways they can. The country’s former president is patrolling the city streets with a civilian defense force, armed with an AK-47. Civilians have been called to find their own weapons and make molotov cocktails — a type of crude, homemade explosive named, mockingly, after a former Soviet foreign minister. Roughly 18,000 weapons have already been distributed in the Kyiv region, according to the government. At the country’s borders, Ukrainian guards...