VIENNA (AP) — After a barrage of airstrikes on cities and military bases around the country, Russian forces were closing in on Ukraine’s capital of Kyiv on Saturday. City officials warned of street fighting and urged residents to stay inside and take cover.

Here are the things to know about the Russian invasion of Ukraine and the security crisis in Eastern Europe:

What is going on in Ukraine’s capitol?

Central Kyiv appeared quiet Saturday. Ukrainian officials reported some success in fending off Russian assaults, but fighting persisted near the capital. Skirmishes reported on the edge of the city suggested that small Russian units were trying to clear a path for the main forces.

With growing signs that Russia aims to overthrow him and his government, Ukranian President Volodymyr Zelenskyy called on Ukrainians to “stand firm.”

U.S. defense officials said they believe the Russian offensive has encountered considerable resistance and is proceeding more slowly than Moscow had envisioned, though that could change quickly.

Kyiv Mayor Vitali Klitschko extended the city’s curfew from 5 p.m. until 8 a.m. He said “all civilians on the street during the curfew will be considered members of the enemy’s sabotage and reconnaissance groups.”

The Biden administration said it was sending Ukraine up to $350 million in arms and other defensive supplies from U.S. stockpiles with another $250 million in defensive support possible. The Czech Republic also approved a plan to send more arms to Ukraine.

Where is Ukraine’s president?

Zelenskyy, Ukraine’s president, has been posting video messages of himself and other national leaders in Kyiv since the invasion began on Thursday but his exact whereabouts were not publicly known.

Zelenskyy was urged early Saturday to evacuate Kyiv at the behest of the U.S. government but turned down the offer, according to a senior American intelligence official with direct knowledge of the conversation. The official quoted the president as saying “the fight is here” and that he needed anti-tank ammunition but “not a ride.”

In his latest message on Saturday, Zelenskyy said Russian attempts to forge into Kyiv have been repelled and Moscow’s plan to quickly seize the capital and install a puppet government has been thwarted.

“The real fighting for Kyiv is ongoing,” Zelenskyy said, accusing Russia in a video message of hitting infrastructure and civilian targets. “We will win.”

Since then, Zelenskyy has posted regular updates on his Twitter account about the various world leaders he has spoken with Saturday, including Turkish President Recep Tayyip Erdogan and Indian Prime Minister Narendra Modi.

In Ukraine, Russian troops march on

Kyiv officials are warning residents that street fighting is underway against Russian forces, who were trying to advance on the city from several directions. They advised residents to remain in shelters or, if home, to avoid going near windows or onto balconies.

The Ukrainian military said a battle was underway near a military unit west of the city center. Mayor Klitschko said new explosions shook near a major power plant that the Russians were trying to attack.

A missile slammed into a high-rise building on the southwestern outskirts of Kyiv, Klitschko said Saturday. He said rescue workers were there and posted an image showing a gaping hole on one side of the building.

Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov claimed Saturday that since the start of Russia’s attack, its military had hit 821 Ukrainian military facilities, 87 tanks and other targets.

Konashenkov didn’t say how many Ukrainian troops were killed and didn’t mention any casualties on the Russian side. Neither his claims nor Ukraine’s allegations that its forces killed thousands of Russian troops could be independently verified.

Konashenkov claimed the Russian military has taken full control of the southern city of Melitopol, 35 kilometers (22 miles) inland from the Azov Sea coast, and said Russia-backed separatists have made significant gains in the eastern region of Donbas.

Ukrainian civilians in harm’s way

Russia claims its assault on Ukraine is aimed only at military targets, but civilians have been killed and injured during Europe’s largest ground war since World War II.

Ukrainian Health Minister Viktor Lyashko said Saturday that 198 people have been killed and more than 1,000 others have been wounded in the Russian offensive. It was not clear whether the figure included both military and civilians.

He said 1,115 other people, including 33 children, were wounded in the Russian invasion.

Some Ukrainians are fleeing for safety

U.N. officials said nearly 120,000 Ukrainians had left the country for Poland, Moldova and other neighboring nations and the number was going up fast as Ukrainians grabbed their belongings and rushed to escape the deadly Russian onslaught.

Miles-long lines of vehicles clogged border crossings, mostly carrying women, children and the elderly. Others came on trains or buses into Poland, Slovakia, Hungary, Romania and Moldova. Authorities in these countries mobilized to receive the Ukrainians, providing shelter, food and legal help. They also eased their usual border procedures, including COVID-19 testing requirements.

“Almost 116,000 have crossed international borders as of right now. This may go up, it’s changing every minute,” said Shabia Mantoo, the spokeswoman of the U.N. High Commissioner for Refugees. “It’s very fluid and changing by the hour.”

The agency expects up to 4 million Ukrainians could flee if the situation deteriorates.

Protestors turn out across the globe to criticize Russia

From Tokyo to London to Taipei, Ukrainians living abroad and hundreds of protesters around the world have turned out on the streets to show their support for Ukraine.

Several hundred Ukrainians living in Japan gathered outside of Tokyo’s main train stations Saturday, chanting “Stop war!” and “Peace for Ukraine.” They held up signs including “No war,” “Stop Putin, Stop Russia,” while others waved Ukrainian flags. At a separate rally reportedly organized by Russian residents in Japan, several dozen people chanted “Hands off Ukraine!”

In Taiwan, demonstrators chanting “Stand with Ukraine” and “Glory to Ukraine” protested outside the Russian representative office on Saturday.

More than 200 Ukrainians gathered outside the Russian Embassy in an Athens suburb Saturday to protest the invasion, chanting slogans and holding posters with messages including “Russia go home,” “Putin burn in hell,” and “We need your help, world!!!”

Turning the sanctions screws on Russia

The West has taken a military option in Ukraine off the table, but world leaders — with the exception of Moscow ally China — are preparing measures aimed at hurting the Russian economy and its leaders, including Russian President Vladimir Putin himself.

The United States, Canada and European allies all announced they are adding direct measures against Putin and his foreign minister, Sergey Lavrov. EU ministers have said even further sanctions were still possible, including booting Russia out of SWIFT, the dominant system for global financial transactions.

Russia on Saturday warned it could react by opting out of its last remaining nuclear arms pact and cutting diplomatic ties.

The deputy head of Russia’s Security Council, Dmitry Medvedev, said sanctions could offer Moscow a pretext for a review of its ties with the West, suggesting that Russia could cut them altogether.

“We may look at each other in binoculars and gunsights,” he said.

He also suggested that Russia could opt out of the New START nuclear arms control treaty that limits U.S. and Russian nuclear arsenals.

Asian and Pacific countries have joined the West in taking punitive measures against Russia, including export controls aimed at starving its industries and military of semiconductors and other high-tech products.

Sporting world turns its back on Russia

Poland is refusing to play its World Cup qualifier against Russia next month in response to Russia’s invasion of Ukraine, the Polish soccer president said Saturday. The match had been scheduled for March 24.

In addition, Russia has been stripped of hosting the May 28 Champions League final by UEFA with St. Petersburg replaced by Paris, and Formula One dropped this season’s Russian Grand Prix in Sochi in September.

The International Ski Federation announced Russia will not host any more of its World Cup events this winter, and the European curling championships scheduled to be held in November in Perm, Russia, will also be relocated.

The International Tennis Federation also canceled all events in Russia indefinitely.

Associated Press writers around the world contributed to this report.