Russian ground forces have evidently executed hundreds of Ukrainian civilians in Bucha, Borodyanka, and Makariv, suburbs or towns west of Kyiv.  These are war crimes, and they are not supposed to happen under the purview of modern military forces.  Nevertheless, they follow a pattern that has been visible in the United States' last few major military engagements.
During the North Korean advance into South Korea in 1950, American divisions experienced attacks on their rear flanks, and suspected North Koreans of hiding among refugees.  In response, leadership commanded ground forces to consider all persons moving toward the American lines as hostile.  At No Gun Ri, American-led forces slaughtered hundreds of refugees fleeing North Korea and the battlefield after pinning them down under a bridge.  The killing went on for three days, and only ended when North Korean advances forced the Americans to withdraw from the area.
In 1968, American forces approached Mỹ Lai in Vietnam, expecting to find a Viet Cong stronghold.  When they arrived, they found little evidence of militia activity, but killed hundreds of unarmed civilians, including elders and children.  Lieutenant Calley shot and repeatedly ordered members of his platoon to fire on unarmed civilians after corralling them into ditches or clearings.  Colin Powell, in an investigation of American forces' treatment of Vietnamese people, failed to find evidence of war crimes and characterized the relationship between the two groups as "excellent".  Military court-martials acquitted every officer involved in the cover-up of the events at Mỹ Lai.  The military only charged fourteen soldiers involved in the killing, and only one ever faced trial.  Richard Nixon commuted Lieutenant Calley's life sentence to three and a half years of house arrest.
In the case of Abu Ghraib, multiple leaders ordered and encouraged the criminal and inhumane treatment of prisoners there.  The detainees included many innocent Iraqis, and many were held without formal charges.  A riot resulted in several dead, and unleashed in the guards a new level of resentment and distrust.  Donald Rumsfeld personally signed off on stress positions, sleep deprivation, and other depraved interrogation techniques, with handwritten comments that suggest tolerance for even harsher treatment.  He reassigned General Geoffrey Miller from Guantánamo Bay to Abu Ghraib, to recreate what he viewed as successes there.  Miller received decoration for his service.  Rumsfeld never faced consequences for his decisions regarding Abu Ghraib.
These events seem to have two things broadly in common:
We do not want to argue that the United States commits more war crimes than Russia, or is normatively worse in its imperialism, or suggest a moral equivalence between nations.  War crimes undermine the United States' geopolitical strategy, and at least most foreign policy and military leaders understand that.  ISAF forces dealt with a tangle of rules of engagement and combatant status in Afghanistan every day, and abided by them on most operations.  That made both strategic and moral sense.
Broadly, it seems that Russia cares less about international law.  This is not even Russia's first set of war crimes in recent years.  They systematically bombed hospitals in Syria as recently as 2019.  The United Nations had explicitly included these locations on no-strike lists provided to Russian leaders.  That good faith now seems quite evidently misplaced.  In one sense, Putin, as a leader of a regional (not global) power, can benefit from undermining the power of international institutions and norms, because a world united against bad actors checks his ambitions more effectively than a fractured world of realist opportunists.  But this strategy quickly bifurcates; it only works if it works, and really does not work if it does not.
Comparing this to relatively isolated incidents rather than systematic ethnic cleansing and genocides implies that this is an isolated incident, or misstep, and not part of a wider Russian campaign of forceful Russification.  But so far—and the situation evolves, making analyses obsolete every day—the instances of outright slaughter have been bounded within the suburbs around Kyiv.  We hope the findings of the last week are exhaustive and not pieces of a larger pattern.  As the truth unfurls and more evidence becomes available, we may need to swap out our historical lens for a more grave one.  Furthermore, it does not align with Russia's strategic objectives, either as stated or as widely understood.  We knew that Russia would seek to imitate the victories it wrought from Grozny-style subjugation.  We knew not to underestimate their potential for brutality.  But this kind of premeditated killing will make occupation more difficult, will harden international opposition, and may offend otherwise ambivalent Russians and Ukrainian Russian-speakers.  If Putin or his lieutenants ordered or condoned these atrocities, or believed they would go unnoticed, then they resulted from yet another miscalculation.
—Lucas