The Russian army said on Thursday that it had destroyed Ukrainian air defense systems and "disabled" air bases across the country, without giving further details.
But the threat did not come only from the sky.
The much feared ground invasion also began on Thursday morning, according to Ukrainian border guards, notably by the east and the separatist region of Lugansk.
Among the Ukrainians of the region, prepared by eight years of armed conflict with the pro-Russian separatist rebels, in this disaster scenario, everyone claims to know what to do.
"If they continue to bombard us, I will find weapons and defend my homeland, no matter if I am 62 years old", threatens Vladimir Levachov, resident of Chuhouïv.
“And yet I am Russian.
But if you look at history, if you read books, there are 300,
400 years it was already the same thing.
Russians are flayers!
“, he enrages.
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On the main eastern roads, the Ukrainian army was everywhere.
Between Kramatorsk and Kharkiv, a column of vehicles bearing the blue-yellow flag is stationary.
300 km away, Mariupol, the main port in the east of the country, powerful explosions shook the city, which has been relatively spared in recent weeks.
In the sector, the first evacuations begin, in particular from the small towns of Zoloty and Gorsky.
"We will take people to the nearest station," said Alexei Babchenko, spokesman for the civil defence.
But further away, in the town of Novotochkovka, such evacuations are now impossible.
A few hours after the start of the offensive, Russian artillery fire was already too heavy and communications complicated.
In Kiev, at dawn, residents taken aback rushed into the metro to take shelter or try to leave the city.
"I was woken up by the sound of bombs, I packed bags and I fled," Maria Kachkoska, 29, told AFP in shock at one of the stations.
Cars full of families were fleeing the capital, as far as possible from the Russian border, located 400 km away.
In Chuhouiv, near Kharkiv, a woman and her son mourned a man killed by a missile, one of the first victims of this attack.
"I told him to leave," repeated the son, not far from the crater dug by the projectile between two five-story buildings.
“I didn't think such a thing could happen, that it would happen in my lifetime,” said Elena Kourilo, a 52-year-old educator.