With Russia's invasion of Ukraine now in its third week, Russian forces appear to be expanding the offensive by striking new areas in the west of the country. Russian President Vladimir Putin has approved the recruitment of "volunteer" fighters from Syria and elsewhere to fight in Ukraine.

The war has forced more than 2.3 million people to flee Ukraine as others try to seek refuge in basements, subway stations and underground shelters.

Ukraine's president, Volodymyr Zelenskyy, said 100,000 people were evacuated over the past two days in the north and center of the country. Humanitarian corridors were agreed to by Russia and Ukraine during cease-fires in those areas. More evacuations are expected, though repeated attempts to reach the besieged port city of Mariupol in the south have failed under continued Russian shelling.

On Friday, Russia appeared to be pushing its offensive westward with authorities in Ukraine saying airstrikes hit two cities that had been far from Russia's main targets elsewhere.

Western nations have been largely united in punishing Russia economically. President Joe Biden is expected to announce Friday an agreement with other nations to revoke Russia's "most favored nation" trade status, allowing for tariffs to be imposed on Russian imports.

The U.S. Congress late Thursday approved a $13.6 billion emergency package of aid for Ukraine and its European allies. Much of that will go toward arming and equipping Ukraine's military, as well as for humanitarian and economic assistance.

Here are some key things to know about the war:

WHAT HAS THE AP DIRECTLY WITNESSED OR CONFIRMED?

Nighttime temperatures in the southern port city of Mariupol are regularly below freezing, and daytime ones normally hover just above it. The city of 430,000 has been without food supplies, running water and electricity for 10 days.

Some 1,300 civilians have been killed in Mariupol throughout the siege, according to Ukrainian Deputy Prime Minister Iryna Vereshchuk. It was not possible to independently verify the figure.

More shelling and airstrikes pummeled Mariupol on Friday. Residents have little idea of the military situation, but know it's not safe to go outside. Looking over the city, two nine-story apartment blocks could be seen ablaze after shelling.

On the outskirts of the capital, Kyiv, AP reporters witnessed a teenage girl recovering at a hospital after her family was ambushed as they tried to flee the area.

WHAT ELSE IS HAPPENING ON THE GROUND?

Russian airstrikes hit near airports in the western cities of Ivano-Frankiivsk and Lutsk. The two cities are far from Russia's main attack targets elsewhere in Ukraine. Lutsk Mayor Ihor Polishchuk said four servicemen were killed and another six were wounded.

Russia said it used high-precision long-range weapons Friday to put military airfields in the two cities "out of action."

Russia's Defense Ministry also said Friday that an offensive, led by fighters from the separatist-held Donetsk region, are further squeezing the city of Mariupol.

Satellite images show a huge Russian convoy that had been mired outside the capital, Kyiv, has fanned out into towns and forests. The immediacy of the threat to Kyiv was unclear.

Three more Russian airstrikes hit the industrial city of Dnipro in eastern Ukraine on Friday, killing at least one person, according to the Ukrainian interior ministry. The city is home to nearly 1 million people.

WHO ARE THE 'VOLUNTEER' FIGHTERS IN THIS WAR?

Putin on Friday approved bringing "volunteer" fighters from Syria and other countries to join Russia's Ukraine offensive. Russia's defense minister said there had been "more than 16,000 applications" from the Middle East, many of them from people who he said fought alongside Russia against the Islamic State group.

Kremlin spokesman Dmitry Peskov confirmed that the recruits include fighters from Syria, where Russia intervened in the civil war in 2015 on the side of President Bashar Assad.

Already, the Ukrainian government says about 20,000 foreigners have joined the so-called International Legion for the Territorial Defense of Ukraine to fight the Russians.

The pro-Ukrainian fighters are given weapons when they arrive. Among them are about 100 of the several thousand Americans who asked to join the fight. The U.K. has warned veterans not to travel to Ukraine to fight there, saying those who do will be court-martialed.

ARE PEOPLE BEING SAFELY EVACUATED?

Ukrainian authorities said there are plans, with support from the Red Cross, for several evacuation and humanitarian aid delivery routes Friday. The top priority remains freeing people from the city of Mariupol and getting aid to its desperate population.

Buses are being sent Friday to multiple Kyiv suburbs to bring people to the capital, where authorities say half of the metropolitan area's population, or around 2 million, has already fled.

There are also efforts to create new humanitarian corridors around the cities of Kherson in the south, Chernihiv in the north and Kharkiv in the east. Russian forces are blockading Kharkiv and pushing their offensive in the south around three cities and towns, including the hometown of Ukraine's president, Kryvyi Rih.

WHAT ABOUT RUSSIA'S CLAIMS THAT BIOWEAPONS ARE BEING DEVELOPED IN UKRAINE?

The U.N. Security Council will meet on Friday to discuss Russia's baseless claims that the United States is conducting "military biological activities" in Ukraine.

The United Nations has said it has received no information that would back up the claim, but that hasn't stopped it from proliferating.

White House press secretary Jen Psaki has called the accusations "preposterous" and warned this week that Russia might use chemical or biological weapons against Ukraine.

China, meanwhile, is amplifying the unsubstantiated and inflammatory claims about Ukrainian bioweapons.

WHAT'S THE VIEW FROM INSIDE RUSSIA?

Putin said Friday that there are "certain positive developments" in Russia-Ukraine talks, without offering any details.

Putin hosted Belarus President Alexander Lukashenko, a close ally, in Moscow for talks on Friday. Putin said he would inform him about the situation in Ukraine and the talks.

Meanwhile, Twitter launched a privacy-protected version of its site to bypass surveillance and censorship after Russia restricted access to its service in the country.

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Follow the AP's coverage of the war between Russia and Ukraine: https://apnews.com/hub/russia-ukraine