But is it really like that? We must compare it with American conquest on Iraq in early 21st century. They need 3 weeks to reach Baghdad. And even with that, they didn't managed to fully captured Iraq. The war was going on longer than that.
And that was Iraq, smaller, surrounded, even besieged by American long before the invasion began. Iraq couldn't even make their own tank and fighter Jet.
At the same time, Ukraine is big, they are not fully surrounded by Russian. They can make their own weapon. Their army is way stronger than Iraq at the time of American invasion.
But half of the Ukraine has the same ethnicity with Russia. Then I believe that Russian won't suffer a prolonged war like American in Iraq after the war is over. At least, as long as they avoid the western part of Ukraine.
Since Russia attacked from Belarus, Ukraine had to make the defense in the city. From the Belarusian border, the troops advanced 100 km and reached Kiev. Even the troops from Gomel advanced 200km, at most.
Russia's strategy was good in this regard, first a fake amphibious operation was launched to the south of Ukraine, then the troops in the east (and the Crimea) began to advance. Meanwhile, the Russian air force struck the bridges and strategic stations on the Dinipier river.
But the main action was the rapid capture of Kiev by the troops entering from Belarus.
Ukraine and Russia have a border of 1100km. The border with Belarus is 900 km. If you include Azov sea, Crimea and the Black Sea, Russia had the opportunity to open and loosen the defense lines of Ukraine for a longer than 3000 km. And he took full advantage of that.
The US invasion of Iraq took place with the power projection of the marine forces from the Gulf and Kuwait direction. Because they entered such a narrow area, they carried out one of the most brutal shock-awe bombardments in modern history. And in these regions, the US received great support from the Shiites, who make up the majority of the Iraqi population.
Ukraine was occupied not today, but in 2014. In the intervening 8 years, neither a European fighter plane nor a tank could be bought. But Saddam was able to buy the latest weapon systems of the period, especially from the French. Saddam's problem was his unwilling army to fight. The USA had destroyed the country from within, before actual invasion.
Ukraine is a country that is %80 surrounded by Russia(land and sea). And it's a country whose armies are totally dependent on foreign aid. For example; Russia seized the jets in 2014(at Crimea), dismantled them and returned them. Ukraine could not even make most of these aircraft fully operational.
Half of Ukraine is not Russian. The population of Russian descent is around 8 million. There are about 35 million Ukrainian descent citizens. Also around 1 million Turkish, Greek and Jewish minorities live. The places where the Russians live, mostly the places where the Turks were deported by Stalin. They settled with the Soviet population policy.
What happened to Ukraine is no less a tragedy than Iraq. Infrastructure was destroyed, possibly triggering a years-long civil war like Syria.
The US invasion of Iraq was a terrible mistake. Its political and economic cost has been very high, and its effects are felt more and more every day. Similar results will occur for Russia.