The recent destruction of two Ukrainian fighter jets over the same rebel territory where Malaysia Airline Flight 17 was shot down is a clear sign that Russia continues to arm and assist the pro-Russian separatists in the Eastern Ukraine.

That alone is ample reason for strengthening economic sanctions on Russia, although by how much and on what economic sectors remains a divisive issue between the United States and the European Union. But the downing of MH17 raises a question of justice that goes beyond politics and requires a separate resolution.

The EU on Tuesday ordered its agencies to come up with new sanctions based on "targeted measures including access to capital markets, defense, dual use goods and sensitive technology including in the energy sector." It also said that sanctions will remain in place until Russia stops "the increasing flow of weapons, equipment and militants across the border in order to achieve rapid and tangible results in de-escalation." The EU urged Russia "to withdraw its additional troops from the border area."

But the European governments are not likely to act on these new sanctions, similar to ones put in place by President Obama before the downing of MH17, until the end of the summer, if then. France vetoed a proposal that arms sales to Russia be stopped because Russia has already paid it for the delivery of a French aircraft carrier. Europeans generally worry that all-out sanctions will deprive them of needed Russian energy supplies.

Also, Germany's spat with the United States over alleged spying by the National Security Agency and the CIA appears for now to be an obstacle to greater coordination of the U.S. and European positions on Russia.

Meanwhile, the Netherlands, which lost 200 of the 298 persons killed on the doomed flight, has called for a careful international investigation to determine who launched the attack. Dutch Foreign Minister Frans Timmerman on Monday told the United Nations Security Council, "Once the investigation ascertains who was responsible for the downing of the flight MH17, accountability and justice must be pursued and delivered."

This is clearly the route to follow. A careful investigation will give lie to the propaganda being put out by Vladimir Putin's government and the Ukrainian rebels that Ukraine was responsible for shooting down MH17 and that their investigation of the crash site would be thorough and honest.

Establishing culpability would be a reasonable prospect if investigators get access to all communications collected by the various intelligence agencies operating in the region.

If the Russian-rebel team is shown to be responsible, as strongly suggested by recently disclosed U.S. intelligence, then Russia and the rebels can be challenged to surrender the perpetrators to be tried, ideally in a Dutch court.

If Russia obstructs the investigation, then Europe will know where it really stands with its reckless neighbor. Then, at least, the climate for rebuilding U.S.-German relations will be greatly improved.