(CNN) -- As the world struggles to come to terms with the horror of another passenger jet falling from the skies, the full picture of how and why Malaysia Airlines Flight 17 came down over eastern Ukraine is far from clear.
The United States believes a surface-to-air missile brought the Boeing 777 down over territory held by pro-Russian separatists but hasn't indicated who's responsible -- though both sides in the ongoing civil conflict in Ukraine blame each other.
According to a top Ukrainian official, the airliner, which was en route to Kuala Lumpur from Amsterdam with nearly 300 people on board, was flying at about 10,000 meters (nearly 33,000 feet) over the Donetsk region of eastern Ukraine when the missile hit.
A number of airlines have since re-routed services away from the region, prompting questions about whether commercial aircraft should be anywhere near conflict zones anyway.
"Was this an accident waiting to happen for any airliner flying over that part of the Ukraine -- and there were plenty of them?" asked CNN aviation expert Richard Quest.
"Although there had been restrictions over Crimea, in this part of Ukraine there are no restrictions. The space between the ground and 32,000 feet had been closed by the Ukrainians. Above 32,000 feet it was open. This plane was not doing anything wrong being where it was.
"We can argue whether restrictions should have been in place with everything going on there, but when that pilot flew that route ... there was nothing wrong with doing so."
"That part of Ukraine is essentially ungoverned space, and when you have ungoverned space you have these kinds of calamities," said retired U.S. Army major general and CNN military analyst James "Spider" Marks. "Sadly, we should not be surprised by this."
"We don't know who had their finger on the trigger, but clearly this is Russian kit, whether in Ukrainian hands or in Russian," he added. Analysts believe this "kit" could be a Buk missile system.
Known as the SA-11 among NATO forces, it was developed by the Soviets and operated by both Russian and Ukrainian forces, according to retired Brig. Gen. Kevin Ryan, director of the Defense and Intelligence Project at the Belfer Center for Science and International Affairs at Harvard University.
As to where the order came from, Marks suggested air defense units could be operating without central control.
"It could be an independent process," he said. "That means individual operators of that launcher or mobile air defense system can engage targets at will based on certain profiles -- they see an aircraft, its altitude, it doesn't transpond in a way they can figure out, so their initial reading is that it's military and they fire because they have the authority. What you'd prefer to have is some back-up systems, but that was clearly not the case here."
With much of the wreckage believed to be in territory held by separatists near the Russian border, there's concern that international inspectors may not be granted access to conduct a proper investigation before the crash site is "contaminated" or tampered with.
"Ultimately, the international community is going to demand that there is a proper, full investigation," said Quest.
Matthew L. Wald, a reporter with the New York Times, told CNN it was important to bring in a skilled investigator to look for clues in the wreckage.
"What you look for in a 'shoot down' or explosion is the condition of the metal. Are there shrapnel holes? Are their entry wounds and exit wounds -- something that went through the airframe? Are there bends in the metal characteristic of high explosives? If someone skilled can find it, they'll be able to make a diagnosis."
He said the aircraft's cockpit voice recorder could also provide vital clues if they survived a possible blast. "You might catch conversations between the crew. This has happened before in airplanes that were shot down, where it's clear pilots were talking to each other about damage to the plane. They know what's happened and that would makes things clearer," said Wald.
"There's no reason why we shouldn't get the recorders," added Quest. "Yes, there was a very violent fire and a very violent crash, but this thing is designed for this."
Yet it's by no means certain that outside assistance will be permitted inside such a volatile area. However, Wald says that there is a precedent for data recovery.
"When the Soviets shot down Korean Airlines Flight 007 (in 1983) ... they said they'd recovered nothing.
"The father of a young college student was on that plane. Hans Ephraimson-Abt went to Moscow, went to (President) Gorbachev and brought back the black box -- and that cockpit voice recorder told a lot."
The friends and relatives of Flight 17 will be hoping they will be spared the anguish of not knowing too.