The agony of the families of the 298 people who died on Malaysia Airlines Flight MH17 lives on. Even a thorough crash investigation might not determine who shot down the plane. Despite calls for stronger action against Russia and its separatist clients in Ukraine, the tragic shootdown changed nothing in practice.

American intelligence reportedly concluded that Russian separatists mistook the flight for a Ukrainian military plane, which seems most likely. If so, then what to do?

The bodies were still warm in Ukraine when America’s hawks began stoking the war machine. Said Sen. John McCain: Involvement of Russia or Russian separatists in the plane shootdown “would open the gates for us assisting, finally, giving the Ukrainians some defensive weapons [and] sanctions that would be imposed as a result of that. That would be the beginning.”

The better answer, however, remains to do largely nothing. The MH17 incident, while outrageous, actually is no trigger for anything. Errant attacks on civilians, while always tragic, are not unusual.

There were several mistaken downings of civilian airliners in World War II. The People’s Republic of China shot down a Hong Kong airliner in 1954, killing 10. A year later, Bulgaria downed an El Al flight, which mistakenly flew into that nation’s airspace. Fifty-eight died. In 1973, Israel shot down a Libyan airliner, killing 108 people, in similar circumstances.

In 1983, the Soviet Union shot down a Korean Air Lines flight, mistaking it for a U.S. spy plane, killing all 269 on board. Five years later, the USS Vincennes shot down an Iranian airliner with 290 passengers and crew. A decade later, Sri Lankan Tamil guerrillas apparently downed an Indonesian airliner, killing 55. In 2001, 78 perished on a Russian flight downed by a Ukrainian missile.

However, in none of these cases did an accidental or erroneous shootdown act as a casus belli. Not once did much of anything happen. Even during the Cold War, such incidents were resolved peacefully.

In the case of MH17, national and international civil air authorities should do better in adjusting air-travel routes to combat realities on the ground. The United States and Europeans also might indicate that another such incident, if tied to Moscow, would result in the grounding of Russian aviation internationally.

Beyond that, however, the United States has no more cause than before for extensive involvement in the Ukraine imbroglio.

Of course, Moscow’s geopolitical machinations are to be deplored. However, Russia is no Soviet Union, and Vladimir Putin is no Josef Stalin. Unlike the USSR, Russia represents no ideological or military threat to America.

In fact, Mr. Putin’s Russia appears to have reverted to a traditional great power, concerned about international respect and border security. Its ambitions are fierce, but bounded.

Moscow’s intervention in Ukraine, like the former’s war against Georgia, is consistent if unfortunate, but such action isn’t likely to lead much further. Indeed, Moscow apparently has no interest in swallowing Ukraine, with a majority of non-Russians (in contrast to Crimea), just like it did not absorb Georgia. Aggression further west is even less likely.

President Obama correctly dismissed the threat posed by Moscow: “Russia is a regional power that is threatening some of its immediate neighbors; not out of strength, but out of weakness.”

The situation facing Ukraine is tragic, but not one of strategic significance to America. The United States never viewed Kiev’s independence as important, let alone vital, when facing the Russian Empire or the Soviet Union.

Kiev’s situation is even less so today. Washington has no security reason to confront Russia militarily, or to risk escalation to military action, over Moscow’s treatment of Ukraine.

The Ukrainians deserve sympathy, of course. Moreover, diplomatic as well as economic pressure to constrain Russian misbehavior is warranted. However, such efforts should have a purpose other than punishment. It would be a mistake to rupture relations with a country that could do much to impede or advance more substantial American objectives elsewhere — Iran, Afghanistan, Iraq, Syria, North Korea and others.

More broadly, it is time for Europe to take over responsibility for its own defense. Russia’s economic and military strength is dwarfed by Europe, which possesses an economy eight times the size of Russia’s and a population three times as great. The Ukraine crisis is primarily a problem for Brussels, not Washington.

The conflict in the Ukraine is a human tragedy. However, the United States has little cause for leading an international campaign against Moscow. Instead, let Europe take the lead in putting its security and prosperity on the line.