John Kerry, minister of Foreign Affairs, stated that the US had intel on the trajectory of the missile that shot down MH17.
However, the US seems to be very cautious about sharing that data. Recently a spokesman of the US government refused to tell what data was handed over the the Dutch investigation team.
Fred Westerbeke, the Dutch prosecutor and lead of the Joint Investigation Team, told that all requested data was handed over by the US to the Dutch Military Secret Service.
You might be wondering why the data was not handed over the the JIT. One of the reasons could be the participation of the Ukraine Secret Service SBU in the JIT. SBU not only has a secret service branch, it also has an investigation branch.
This article of an Ukraine news agency states SBU is involved in the JIT as SBU staff attended a meeting in which the JIT agreement was extended.
There are still officers working at the SBU whose sympathies lie with Moscow according this article in Irish Times. For that reason, the US is known to be highly selective about the intelligence it shares with Ukraine in case it falls into Russian hands. Satellite images, for example, are degraded before they are shared with the SBU.
Mashable had a story titled Ukraine’s top intelligence agency deeply infiltrated by Russian spies
This could be a valid reason to not directly share information with the JIT.