The Big Questions of the Ukraine Conflict as Russia Continues Assault on Its Neighbor

As the situation in Ukraine continues to rapidly unfold after day two of a Russian invasion, there remain several questions: How many casualties have been seen, for instance, and how far will Russia go? While some things have been confirmed, others are more fluid, seemingly changing by the minute.

Here's what we know — and what we don't — regarding the Russian invasion into Ukraine.

How many casualties have there been?

The true toll of the Russian invasion so far isn't known, though Ukraine says that at least 137 people have been killed so far as Russian forces advance towards the capital, Kyiv. The number of Russian dead has not been released.

In a statement released Friday, a spokesperson for UN High Commissioner for Human Rights Ravina Shamdasani said Ukrainian civilians are "terrified."

"We are gravely concerned about developments over the course of the day yesterday and overnight in Ukraine. We are receiving increasing reports of civilian casualties," the spokesperson said.

The statement continued: "Civilians are terrified of further escalation, with many attempting to flee their homes and others taking shelter where possible. As the High Commissioner has warned, the military action by the Russian Federation clearly violates international law. It puts at risk countless lives and it must be immediately halted."

Where are Ukraine's leaders?

By all accounts, Ukrainian leaders — including President Volodymyr Zelenskyy — remain in Ukraine's capital in Kyiv.

"[The] enemy has marked me down as the number one target," Zelenskyy said in a video message posted Friday. "My family is the number two target. They want to destroy Ukraine politically by destroying the head of state."

He continued: "I will stay in the capital. My family is also in Ukraine."

Prior to the invasion, Zelenskyy had asked to hold discussions with Russian President Vladimir Putin, who responded the two could meet in Minsk — albeit under unclear conditions.

In remarks delivered as Russian troops grew closer to Ukraine's capital in Kyiv on Friday, Zelenskyy said, "I would like to address the President of the Russian Federation once again. Fighting is going on all over Ukraine. Let's sit down at the negotiating table to stop the deaths of people."

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Zelenskyy has also responded to Putin's continued claims of "genocide" and use of the word "Nazi" to serve as a pretext for invading Ukraine. In declaring war on the country Thursday, Putin said his operation would oversee a "demilitarization and de-Nazification" of the country.

As fact-checkers have noted, there has been no genocide in Ukraine, and its president, Zelenskyy, is Jewish. "How could I be a Nazi?" he said in response to Putin's claims, directing remarks at the Russian public while speaking in Russian (his native language): "The Ukraine on your news and Ukraine in real life are two completely different countries — and the main difference between them is: Ours is real. You are told we are Nazis. But could a people who lost more than 8 million lives in the battle against Nazism support Nazism?"

What territory in Ukraine is controlled by who?

Two southeastern regions of Ukraine — Donetsk and Luhansk, which are collectively referred to as Donbas — have been controlled by Russia-backed separatists for nearly eight years, after Ukraine's pro-Russian President Viktor Yanukovych was driven from office by mass protests in February 2014.

Russia responded to those protests by annexing Ukraine's Crimean Peninsula and sending in Russian-backed rebels to seize government buildings in Donbas.

Al Jazeera reports that entering those separatist-controlled regions has been nearly impossible in recent years, even for Ukrainians, who would be required to first enter into Russia and would have to have relatives in Donbas (who are required to have a Soviet-era residency registration) to visit.

Following extensive fighting over the region, Russia and Ukraine brokered a 2015 peace deal — one that ultimately collapsed this week, after Putin officially recognized Donbas as "independent," paving the pay for his troops to invade the areas.

What sanctions have been imposed and what impact will they have?

President Joe Biden said he was increasing economic sanctions against Russia on Tuesday, following Russian President Putin's decision to recognize two separatist-controlled regions of Ukraine as "independent" (a move the president noted served as a precursor to an invasion).

That first round of sanctions targeted two large Russian banks, Russia's sovereign debt, and froze the American assets of individual members of the Russian elite and their relatives.

Biden warned of more severe sanctions "if Russia goes further with this invasion," a promise he kept on Thursday when he put in place escalated sanctions after Russia began attacking Ukraine. The harsher sanctions included freezing the assets that Russia's largest bank and four other Russian financial institutions held in America; and cutting Russian high-tech imports in half.

In terms of actually deterring war, sanctions have a mixed record historically, because they don't typically yield much of an impact over night. Months or years down the line, though, they could greatly impact Russia's ability to do business in the global economy, isolating it and diminishing its power over time.

Other countries have also announced sanctions against Russia, with Germany halting the planned Nord Stream 2 natural-gas pipeline on Tuesday and the U.K. announcing additional sanctions Thursday, including the freezing of both Putin's and Russian foreign minister Sergei Lavrov's foreign assets (a move that reports suggest is being mulled by the Biden administration, as well).

How will the world respond next?

Though harsher sanctions are likely, world leaders have so far not indicated that a military response will come from other nations (aside from Ukraine, where civilians are attempting to defend the country alongside the military).

President Biden has said he will not send American troops to fight Russian forces in Ukraine and has pulled U.S. troops out of Ukraine in recent weeks to avoid a clash.

"These are totally defensive moves on our part," the president said Tuesday, adding: "We have no intention of fighting Russia."

Despite the west sending military aid, Ukrainian President Zelenskyy has suggested his country needs more, saying this week: "When bombs fall in Kyiv, this happens in Europe, not only in Ukraine. When missiles kill our people, it's the death of all Europeans. Require more protection for Europe, more protection for Ukraine — as part of a democratic world."

NATO has so far sent extra troops and aircraft into member states near Russia but the U.S. and other NATO countries like the UK and Germany are resistant to get involved in military combat due to Ukraine not being a NATO member.

But with its invasion of Ukraine — historically the buffer between Russia and the West — Russia has extended its military powers to the borders of NATO countries such as Poland, causing fears that Putin could eventually look to recreate the old Russian empire.

The Russian attack on Ukraine is an evolving story, with information changing quickly. Follow PEOPLE's complete coverage of the war here, including stories from citizens on the ground and ways to help.