LONDON — A century on from World War I, nobody wants the guns of August.

Yet it must be asked if waiting years for the evasive conclusions of an official investigation into the fate of Malaysia Airlines Flight 17 is better than acting now on what we already know: That the Boeing 777 with 298 people on board was shot down by a missile from a Russian-made SA-11 antiaircraft system fired from an area of eastern Ukraine controlled by Russian-backed separatists, Russian mercenaries and Russian agents. A half-drunk Ukrainian peasant with a 1950s-era rifle doesn’t shoot down a plane at 33,000 feet.

An “enormous amount of evidence,” in Secretary of State John Kerry’s words, points to Russian provision of SA-11 systems and training. The Ukrainian government has damning audio and images that capture the crime. In June, a Ukrainian cargo plane landing in the area was hit with shoulder-fired missiles, killing 49 people. This month, another cargo plane flying at 22,000 feet was hit by a missile. Rocket science is not required.

President Vladimir Putin of Russia has been playing with fire. His irredentism has made him a hero in Russia. It has endangered the world. Crimea was the swaggering precedent to this crime. The shooting down of Malaysia Airlines Flight 17 amounts to an act of war. It was impromptu perhaps, but still. Dutch corpses have rained down on the sunflowers and cornfields of eastern Ukraine, to be defiled even in death, 193 innocent Dutch souls dishonored by the thugs of the Donetsk People’s Republic.

“This is murder, mass murder. Let’s call it what it is,” said Julian Lindley-French, a defense analyst who lives in the small Dutch village of Alphen. “Shock is turning to anger here,” he told me, “and that anger will resonate in the coming weeks. This is the beginning of a period of complex torture for the Netherlands.”