It is being reported that the US has requested Malaysia to "be transparent" and share the known information to eliminate confusion and speculation
The Malaysians' trust in the US may be ebbing as many of the recent stories come from 'US sources', i.e. leaks, and are critical of the Malaysians.
If there is sensitive data you really need to know it's not going to go any further.
"Be transparent" could mean anything up to "we know exactly what happened to the airplane and we know that you know. And we are giving you a chance to announce it first." Just saying.