Ukrainian soldiers in the small town of Severodonetsk, Donetsk Region on February 27, 2022.Ukrainian soldiers in the small town of Severodonetsk, Donetsk Region on February 27, 2022.

More than four days into Russia's invasion of Ukraine, the smaller country's defenders are not giving up.

According to the latest intelligence update from the U.K. Defence Ministry, the capital of Ukraine, Kyiv, and its second-biggest city, Kharkiv, are still in Ukrainian hands.

Russian forces are continuing to advance into Ukraine from multiple axis but are still being met with stiff resistance from the Ukrainian armed forces, according to the ministry.

The situation in Kyiv is calm, the capital is completely controlled by the Ukrainian army and defense, according to Mykola Povoroznyk, Kyiv's first deputy head of administration.

The situation on the ground in Ukraine is constantly changing and it is difficult to confirm individual military accounts.

According to the U.K. Defence Ministry, fighting was taking place around the city of Kharkiv.

A senior U.S. Defense official said on Sunday that Ukrainian defenders hold on to Kherson, a third major city targeted by Moscow planners.

Russian advances were being slowed by shortages of fuel and other supplies in Kharkiv, as well as the advance to Kyiv, according to a Defense official.

The UN Security Council met in an emergency session to head off war after Putin ordered the invasion of Ukraine.

Since then, the United States, European Union and even Germany have committed to new weapons shipments to Ukraine as the country's defenders have held out against the Russian onslaught.

Western corporations and governments are introducing new economic measures against Russia.

The U.S. intelligence predicted the invasion in the weeks before Putin ordered it, and the Russian president demanded guarantees that the country wouldn't join NATO.

Secretary of Defense Lloyd Austin said in a statement that Mr. Putin doesn't want a strong NATO on his western flank.

Ukrainian refugees cross the border into Poland.