The Russian invasion of Ukraine, which officials say was a violation of international law, happened early Thursday morning local time while the United Nations Security Council held an emergency meeting. Ukraine requested the meeting, hoping to stave off an invasion. The meeting ended with Ukraine's ambassador telling his Russian counterpart, "There is no purgatory for war criminals. They go straight to hell."

Fritz Mayer, dean of the Josef Korbel School of International Studies at the University of Denver, said the invasion likely comes as an "absolute shock" for many people in Ukraine.

"The consequences are severe, certainly in terms of personal freedoms and the politics of this," Mayer said. "Russia may well have a hard time controlling the territory if it conquers it, and I think they will."

President Joe Biden said Putin “has chosen a premeditated war that will bring a catastrophic loss of life and human suffering." Biden met with leaders of G-7 countries Thursday and delivered a public address after the meeting in which he announced new sanctions against Russia and emphasized that U.S. forces will not engage in combat in Ukraine.

"Our forces are not going to Europe to fight in Ukraine, but to defend our allies in the East," the president said during his remarks.

A recent poll found that a majority of Americans do not want the U.S. to have a “major role” in the conflict.

Both the U.S. and members of the European Union have said they will impose “severe” sanctions on Russia. Those sanctions, paired with armed conflict, are expected to disrupt an already fragile global supply chain.

Putin has said his decision to invade Ukraine stemmed from security concerns. Ukraine has expressed interest in joining the North Atlantic Treaty Organization (NATO), an intergovernmental military alliance between more than two dozen countries, including the United States, that was formed after World War II to provide security against the Soviet Union. Putin said Ukraine, which was part of the USSR until its collapse in 1991, joining NATO would be a “hostile act.” In December of 2021, Putin demanded NATO deny membership to Ukraine and other ex-Soviet countries. The demands were rejected.

[Related: Why NATO and Ukraine are a flash point with Russia 30 years after the end of the Cold War]

Mayer said Russian's invasion of Ukraine "undermines the whole international order: The idea that countries don't go to war to seize territory from other countries, that national borders are sovereign. The whole post-World War II order is really under threat here."

Before the invasion, Ukrainian President Volodymyr Zelensky pleaded with Russian civilians to stop their government from launching an attack. “This is our land. This is our history. What are you fighting for and with whom?” he said to the people of Russia. “Many of you have been to Ukraine. Many of you have relatives in Ukraine. Some have studied in Ukrainian universities. Some have made friends with Ukrainians. You know our character. You know our people. You know our principles.”

After the invasion, Zelensky — who had said previously that Ukraine would “fight back” if Russia invaded — urged Ukrainians to take up arms, donate blood and support the country’s military. He said any Ukrainian who wants to defend the country could pick up firearms from the military.

Putin, in televised remarks, said countries that attempt to intervene will face "consequences greater than any you have faced in history."

Russia’s defense ministry said its forces are targeting Ukrainian military posts, not civilians. A senior U.S. defense official told The Associated Press that so far, Russia’s main targets have been airfields and ammunition warehouses. The AP reported Thursday afternoon that Ukrainian officials said close to 60 people had been killed in the attacks. It is unclear if those casualties included members of the military, civilians or both.

For the most part, the condemnation of Putin has been bipartisan. U.S. Rep. Diana DeGette (D-Colo.) said “There’s a special place in hell for people like Vladimir Putin” while Colorado Sen. Michael Bennet (D) said Putin’s “violent path will result in grave consequences not only for the Ukrainian people but for the Russian people as well.” Republican Senators, including Marsha Blackburn (Tenn.) and Lindsay Graham (S.C.), have joined calls for harsh penalties against Russia and Putin.

Not everyone is on the same page. Former President Donald Trump praised Putin’s plotting as “genius” and “savvy,” while Colorado Republicans Rep. Lauren Boebert and Rep. Ken Buck used the worsening conflict to target  Biden.

Colorado Governor Jared Polis released a video detailing the ways Colorado will be withdrawing any support for the Russian government. The governor also said Colorado is ready to welcome Ukrainian refugees.

Asked how he thinks this conflict will end, Mayer told Rocky Mountain PBS that in the short term, it is likely that Russia will take control of Ukraine due to the asymmetry in the sizes of their respective militaries.

"It's not hard to imagine that in a relatively short time, Ukraine will be under Russian control," he said. "So the real question is the long term."

Mayer said the sanctions imposed on Russia will cause some "pain" for the West in terms of things like rising energy prices — as much as 40% of Europe's natural gas is supplied by Russia — and that sanctions only work if they are sustained over a long period of time. Mayer's bet is that the U.S. and its allies will not be able to stay the course as Biden said they would during his press conference.

"My guess is that Putin's bet is that we won't stay the course," Mayer said. "He knew that these sanctions were coming. But I'm guessing he thinks — and he's said as much — that the West is too weak and doesn't have the resolve [to maintain the sanctions]. So a thing we can all do, I think, is be patient and stay the course."

Kyle Cooke is the digital media manager at Rocky Mountain PBS. You can reach him at kylecooke@rmpbs.org.

Julio Sandoval is a multimedia journalist at Rocky Mountain PBS. You can reach him at juliosandoval@rmpbs.org.

Alexis Kikoen is a senior producer at Rocky Mountain PBS. You can reach her at alexiskikoen@rmpbs.org.