I think Putis is trying to minimize the number of civilian casualties during this war. Otherwise he could have covered every centimeter with bombs and only then send infantry.
Or he is just creating a thread, waiting for Ukraine to surrender and accept independent republics. He just wait, fire missiles, throw bunch of troops and vehicles, and wait. Hit and wait tactics. Otherwise he would have sent strategic bombers and in hours there will be a burned land everywhere.
I think that he wants to achieve the objectives with minimal losses including civilians, but he is not hesitating on bombarding densely populated cities and my take is that it will get worse. Blanket bombing, fuel-air massive bombardments,... Ukraine is going to pay a heavy price for their freedom to choose their own future, but if they prevail the blow will hit Putin badly and he may face insurrections in other territories.
This is starting to look Grozny.
I’m not sure about Crimea, but Ukraine has seen a supply of the missiles below. They won’t stop the overall result, but initially, even in relatively unskilled hands, it looks like they are slowing the pace of the destruction, and causing the Putainians to think.
Stinger missiles:
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Javelin missiles:
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These are both decent systems. The Javelin in particular costs 100k USD each and can pretty much disable any main battle tank, realistically, at 600m. The stinger unfortunately has a limited altitude (realistically 5000 m) range and, while very effective against helicopters, is no so much against modern fighters and has zero use for high altitude drones or bombers.
These usually are defensive weapons, they would not enable a counter-attack. They could allow a guerrilla warfare, but still Europe and US need to send air defence systems, tanks, planes,.. the "good stuff".
A very simple tool that could be very effective due to the composition of Putin's invading army are the smaller, cheaper yet effective for medium and light armour RPGs and German anti-tanks.