But Hillary Clinton, the former US secretary of state, was more potent in her statements, saying in a television interview that indications pointed at the Russian-backed side and action was needed to "put [Vladimir] Putin on notice that he has gone too far and we are not going to stand idly by".
Clinton said in an interview with Charlie Rose on the American PBS network: "The questions I'd be asking is, number one, who could have shot it down? Who had the equipment? It's obviously an anti-aircraft missile. Who could have had the expertise to do that? Because commercial airlines are big targets, but by the time they got over that part of Ukraine they should have been high, so it takes some planning [to target such a plane].
"And the Ukrainian government has been quick to blame it on terrorists, which is their name for the Russian insurgents. And there does seem to be some growing awareness that it probably had to be Russian insurgents.
"Now, how we determine that will require some forensics, but then if there is evidence pointing in that direction, the equipment had to have come from Russia. What more the Russians may or may not have done, we don't know.
"Europeans have to be the ones to take the lead on this. It was a flight from Amsterdam to Kuala Lumpur over European territory. There should be outrage in European capitals."