Shortly after the crash of MH-17 – the Malaysian airline that went down over Ukraine – the cause of the crash seemed clear-cut.
American and Australian reports said the aircraft, on a scheduled flight from Amsterdam to Kuala Lumpur, was shot down by a missile fired by Russian separatists on July 17, 2014, killing 283 passengers and the 15 crew aboard.
Our then prime minister, Tony Abbott, had no doubt what had happened. He said Russian-backed rebels appeared to have killed Australians using Russian-supplied heavy weaponry. He then added, "I mean this is not an accident, it is a crime. I stress it is not an accident, it is a crime and criminals should not be allowed to get away with what they have done."
Saner voices suggested the downing of the plane was not intentional. Pro-Russian separatists would gain nothing from shooting down a passenger airliner.
The most likely explanation was that separatists had fired a missile at what they thought was a Ukrainian military aircraft. Ukrainian planes had been bombing pro-Russian towns. In the week before the downing of MH-17 the BBC reported that 11 people had died when the rebel-held town of Snizhne in the Donetsk region was bombed.
The Dutch investigation concluded in October 2015 that the crash was due to a warhead that detonated outside the front of the plane, carried by a missile used in Russian BUK systems.
The separatist missile theory was given added weight when the US Secretary of State, John Kerry, said shortly after the crash that the US had observed the moment of the shoot-down and detected a launch from the separatist area with a trajectory that showed it went to the aircraft.
He repeated this in August 2014 in a joint press conference with our Foreign Affairs Minister, Julie Bishop, and then minister of defence David Johnston. Kerry said, "we saw the trajectory, we saw the hit, we saw this airplane disappear from a radar screen. So there's really no mystery about where it came from and where these weapons have come from."
Having announced that they were monitoring this war zone it would seem to be just a matter of course for the United States authorities to provide Dutch prosecutors with the evidence.
But for some reason this is not what has happened.
The issue was raised directly at a US State Department media briefing on March 2 when a Russian reporter asked about a letter the Dutch Public Prosecution Service had written to relatives of victims of the crash.
The reporter put it to the State Department official that in the letter the prosecutors said they did not have (a) any raw radar data or (b) any images of the location from which the missile was launched, due to a clouded sky at the time.
The State Department official, Mark Toner, said he believed the US had collaborated with the Dutch investigation but he did not know to what level of detail.
The matter was followed up the next day when State Department official John Kirby was asked what kind of data the US had shared with the Dutch investigators.
Mr Kirby said he was not going to be able to give a lot of information. Asked specifically if the data included satellite images or radar data he repeated, "I'm not going to be able to give you much on that."
When it was pointed out that he had not given any information at all, he said, "We continue to work with the joint investigation team and law enforcement authorities. But I'm not going into the details of co-operation."
The Canberra Times has asked the State Department for an update but has received no response by the time of writing.
The latest reports out of Holland say the Dutch-led team carrying out the criminal investigation should soon determine the exact launch site of the missile.
It's widely expected that they will confirm that the missile was launched from separatist-held territory.
So what explanation can there be for the US reluctance to pinpoint the launch site and say what kind of monitoring information they have and what information they have given to Dutch authorities?
Could it really be that Kerry was not telling the truth and they don't have the data? Or do the Americans want to keep their surveillance operations secret?
No-one – and certainly not the Russians – would be surprised that the Americans were monitoring this war zone with every means at their disposal. There's no secret there. What point is there in now trying to hide the satellite and radar data?
Could it be that the Americans no longer want to finger the Russians?
Given all the past talk, that would be a major turn of events.
But in recent months Kerry has been working with the Russians to resolve the civil war in Syria and achieve a peaceful political process for a long term solution.
Could it be that co-operation with the Russians to solve this crisis is now more important than trying to embarrass the Russians over the MH-17 crash?
Certainly the cold-war rhetoric seems to have been toned down in recent weeks.
There are also precedents for accepting that this sort of accident can happen, not least the shooting down of an Iranian A300 Airbus by the US missile cruiser Vincennes in July 1988. The airliner, in Iranian airspace, over Iran's territorial waters and on a scheduled flight, was shot down by the Vincennes which apparently mistook it for a much smaller F14A Tomcat fighter. All 290 people on board the plane died.
It took until 1996 for the US to reach a settlement and express deep regret over the loss of life.
Hopefully the relatives of the victims of the MH-17 crash, including the 38 Australian citizens and residents who died, will not have to wait so long to hear a full admission of what happened and get a full apology.