When the Australian official took the podium to explain to reporters the discovery of satellite images that might show pieces of MH370, he carefully omitted to tell them the source.
The images were from a US satellite. The Australian Maritime Safety Authority's John Young didn't mention this to the media. Nor was he asked. But he wouldn't have disclosed it in any case.
As ever, Australian officialdom is hyper protective of US intelligence and its sources - even more protective than the Americans themselves.
The US decision to share its satellite imagery was just one part of the international co-operation involved in the 26-country search and rescue effort.
The satellite imagery of many nations has been carefully "scrubbed" by analysts in the search for the Malaysia Airlines jet, a painstaking task. "This is human eyeballs working through a vast number of images," said an official involved in the effort.
And just as quickly as Tony Abbott was briefed on the potential find on Thursday, he decided he should phone his Malaysian counterpart to brief him.
Pressure on Najib Razak has built every day of the agonising 12 days of the search. He was on the phone to Mr Abbott around 1pm, within half an hour of Australian officials requesting the call.
After Mr Abbott set out the scant facts of the sighting of potential debris in the Indian Ocean 2500 kilometres south-west of Perth, Mr Najib thanked the Australian Prime Minister for the search effort and the call. He asked to be kept informed of any major developments.
The Australian government has also given priority to keeping China informed.
In the Australian hierarchy, "Malaysia has the primary claim on this because it's their plane," said an official, "then China because of the number of Chinese passengers, then the US because it's a Boeing."
Australia's Department of Foreign Affairs phoned the Chinese ambassador to Canberra, Ma Zhaoxu, to tell him the news before Mr Abbott rose to inform the Australian Parliament a few minutes after 2pm.
The two countries have been considering taking the co-operation to a higher level. Chinese and Australian officials have held preliminary discussions on bringing the Chinese military into the search.
By Thursday night, the three countries participating in the Australian-co-ordinated search were all members of the so-called Five Eyes intelligence-sharing alliance. Australia had dispatched four Orion P3 maritime surveillance planes, New Zealand had sent another and the US had contributed a Poseidon submarine-hunting plane.
According to an official, Australia had not yet asked for any particular Chinese assets, nor had Beijing offered, but "preliminary planning discussions" had been held.
Officials were keenly aware of two considerations. One, if the apparent debris is part of MH370, a long search and recovery effort could lie ahead.
Two, it was vital to avoid leaping to conclusions, especially after 12 days of false leads and faded hopes.