WASHINGTON

The airspace above Ukraine continues to be contested and Russia does not have air superiority over the entire country, a senior US defense official said Tuesday.

"But there are areas where they have more control than others. And the same goes for the Ukrainians," the official told reporters, speaking on condition of anonymity.

The official said as early Tuesday, more than 400 missiles were launched into Ukraine, which was a mix of short-range and medium-range cruise missiles.

"The Ukrainian air and missile defense systems remain viable and intact and engaged," said the official, adding that Ukrainian President Volodymyr Zelenskyy has command and control of his army.

On the sixth day of Russian attacks on Ukraine, a convoy of Russian tanks and vehicles are moving closer to Kyiv and Moscow has reportedly warned residents in the capital to leave ahead of planned attacks.

Since the Russia-Ukraine war began last Thursday, it has been met by outrage from the international community, with the EU, UK, and US implementing a range of economic sanctions on Russia.

At least 136 civilians, including 13 children, have been killed and 400 others, including 26 children, injured in Ukraine, according to UN figures.

Around 660,000 people have fled Ukraine to neighboring countries, the UN Refugee Agency said on Tuesday.

*Kasim Ileri contributed to the story.