Says America: Putin has used two-thirds of his fighting power, and 320 missiles have been launched today.

Russian President Vladimir Putin has used two-thirds of the total Russian combat force “for this invasion”, a senior US defence official told reporters Sunday, CNN reports.

“That means he still has a third outside Ukraine, which is not insignificant”, the American official said.

The United States has estimated that since today Russian forces “have launched more than 320 rockets”.

Most of these missiles are the short-range ballistics strategy”, the US official added.

Ukrainians today had the fourth day of fighting for their country, while Russian forces had managed to enter Kharkiv, Ukraine's second largest city.

However, the city is now under control by locals, even though hundreds of Russian troops had first broken resistance.

Ukrainian authorities show Russia's plan, however, is not going as predicted.

While all the world's attention is in Kiev, the Ukrainian capital continues to remain “invulnerable”. Ukrainian authorities, when speaking of victories, refer to the mass of fighting in the capital, where civilians are helping to keep invading forces as far away as possible.

Citizens in some parts of the cities are equipped with Molotov to attack Russian tanks.

In the afternoon, Ukraine agreed to take a delegation to the Belarus border Monday to negotiate with the Russian delegation in an effort to end the war.

Zelensky himself has announced that he has spoken on the phone with Belarus's president, Alexander Lucashencon, ally of Russian President Vladimir Putin.

The resolution of the conversation with Alexander Lucas. We have agreed that the Ukrainian delegation will meet with Russian without pre-emptive conditions at the Ukraine-blarus border in the area of the Pripyat” River, Zelensky wrote on Facebook.

Ukrainian President Lukashenko said he has claimed responsibility that aircraft, helicopters and missiles deployed on Belarus territory will remain on the ground along the departure, negotiations and the return of the Ukrainian delegation to the country.

Belarus is Russia's ally and has played a key role in the Russian invasion of Ukraine. Russian troops invaded Ukraine's border with Belarus with the support of the Belarusian government, according to Ukrainian officials.