The US corporate media are awash in fevered articles and news stories about a Russian "invasion" of Ukraine, as though it was 1938, with German troops marching into Sedetenland and Austria. But let's step back and look at what's going on, calmly and rationally.
Ukraine, the eastern half of which nation has historically been a part of Russia (the western part having in the past been a part of Poland), is in truth an ethnically and geographically divided "nation," composed of Ukrainians, the majority of whom live in the western part of the country, and ethnic Russians who, while a minority within the whole of Ukraine, are a majority in the eastern part of the country.
After the pro-Russian elected prime minister of Ukraine Victor Yanukovych was driven out of office and out of the country in a putsch earlier this year, financed and backed politically by the United States, the new post-putsch government in Kiev begin instituting or threatening to institute laws that were viewed as threatening and repressive by the Russian minority in the east -- things like restrictions on the use of Russian language, for example. As a result, the Ukrainian Russians rebelled, declaring their several regions to be autonomous republics. In Crimea, where Russians are the overwhelming majority of the population, an election was held on whether to leave Ukraine altogether, and rejoin Russia. It passed overwhelmingly, with over 90% of voters opting for reunion with Russia. Russia's parliament agreed to annex that region, which not incidentally hosts Russia's only southern naval base (it was at the time being rented to Ukraine on a long-term lease).
Subsequently, the Ukrainian government launched a military campaign, increasingly violent and bloody, to put down the rebellion in the "autonomous" regions of Lugansk and Donetsk, as well as in the cities of Odessa and Miriupol. After some 2200 civilians had been killed by indiscriminate Ukrainian shelling, rocket bombardments and aerial bombing of eastern cities by the Ukrainian airforce, and by armed thugs in Odessa and Mirapol, with the outgunned separatist rebel forces being pushed back into the centers of the of Lugansk and Donetsk, where their situation looked increasingly desperate, Russia has apparently responded. It did this either by a direct intervention of Russian troops and armor, as claimed by the Ukrainian government, or by allowing Russian volunteers to cross the border and join the fight, as claimed by Russia. The result, either way, has been a rout of Ukrainian forces, who are now in retreat.
Russia's increased military involvement in Ukraine, and the Ukrainian military's abject collapse in the face of that involvement, has US officials, and the once war-mongering US corporate media, apoplectic. The Russians are coming! The Russians are coming! America needs to act!
Now let's pause a moment and take a page here from Noam Chomsky to conduct a thought experiment:
Imagine for a moment that Mexico's elected government was just recently overthrown by a violent putsch, financed by some $5 billion in Russian money funneled to pro-Russian activists in the country, and that the new pro-Russian government installed by the putschists then began a military campaign against the pro-US Mexicans living in the 50-mile-wide strip of Mexico just south of the US border (I don't know if there are any pro-US Mexicans living there, but let's at least pretend there are). Imagine that the Mexican military began indiscriminately shelling and bombing towns like Juarez, Tijuana and Encinada -- places filled not just with pro-American Mexicans, but with many Americans who have vacation homes or who manage maquiladora factories across the border from the US. Imagine that several thousand Americans in those areas had already been killed by the Mexican military's attacks.