Western intelligence officials repeatedly said over the weekend that Russian forces have encountered "stiffer than expected" resistance from an outmanned and outgunned Ukrainian military.

As a result, Russia has thus far failed to take key cities across Ukraine, including the capital Kyiv. On Sunday, Ukrainian forces successfully repelled a Russian advance on a strategic airfield near Kharkiv, Ukraine's second-largest city, which has been under near-constant attack.

However, the situation on the battlefield could change very quickly as Russian forces keep up their assault. They still greatly outnumber Ukrainian forces, and Russia continues to maneuver its units into position around major urban centers.

A senior US defense official reportedly said on Sunday that Russia has only used two-thirds of the total combat power applied to the mission, leaving a significant amount of forces available to press the offensive.

And on Monday, a miles-long convoy of Russian military vehicles was bearing down on the Ukrainian capital, Kyiv, while intelligence also suggests Belarus is prepared to join the Russian invasion.

Putin, who probably thought Ukrainians would greet his tanks with flowers, might have misjudged not only the country's ability and will to defend itself, but also just how hard a line the international community would take against Russia in the face of an invasion.

For years, the Russian president has faced very little pushback from the West over his annexation of Ukraine's Crimea peninsula, his brutal support for the Syrian regime, and aggression in Georgia.

All their strong words aside, Western countries still bought gas from Russia, offered a safe haven to its rich oligarchs, and retained relatively normal diplomatic relations with Moscow.

But this time, the Western world and its allies are united like never before. From unprecedented sanctions that are already hurting the Russian economy to international sport slowly departing from the regime, even Switzerland will forego its famous neutrality.

"Russia's attack is an attack on freedom, an attack on democracy, an attack on the civil population, and an attack on the institutions of a free country. This cannot be accepted regarding international law, this cannot be accepted politically, and this cannot be accepted morally," Swiss Federal President Ignazio Cassis said.

"To play into the hands of an aggressor is not neutral. Having signed the Geneva convention of human rights, we are bound to humanitarian order. Other democracies shall be able to rely on Switzerland; those standing for international law shall be able to rely on Switzerland; states that uphold human rights shall be able to rely on Switzerland."