US surveillance data
In view of the fact that Obama has already stated that the USA has data showing the use of a SA missile to bring this aircraft down it seems perverse in the extreme not to make some of the raw data available right away, even if in limited resolution. Not doing so just helps accelerate the storm of disinformation.
In the case of a "normal" accident investigation you could say that holding back would be prudent however given the likelihood that other evidence is already compromised revealing some of the data might at least shut down some of the disinformation.