In March 2012 Ukraine reported completing removal of HEU from its territory, fulfilling the pledge made by the president of Ukraine at the 2010 Nuclear Security Summit. Removal of HEU was done as part of the GTRI program that works on global HEU cleanout.
A small amount of HEU, however, remained in Ukraine - a report in Zerkalo Nedeli, a Ukrainian weekly, published the U.S.-Ukrainian Memorandum of Understanding (PDF in Ukrainian), which states that (translation from Ukrainian, emphasis added)
2. Ukraine undertakes to work together with the United States to
a) Carry out all necessary internal procedures in order to remove all the remaning HEU with the exception of a small amount of materials, as agreed by the Parties, which is sufficient for carrying out fundamental scientific research and for successful construction of the new LEU-based neutron source.
In the interview given to Zerkalo Nedeli, Ivan Karnaukhov, the director of the project that works on the construction of the neutron source mentioned in the memorandum - an accelerator-driven subcritical assembly - confirmed that some HEU remained at the Kharkov Institute of Physics and Technology, but did not disclose the amount.
This amount of HEU left in Ukraine appears to be very small, probably on the order of tens or a few hundred grams. A study done at the Argonne National Laboratory estimated that even if the assembly were to use HEU fuel, it would contain less than 1 kg of HEU (17 VVR-M2 fuel assemblies). Any amount of HEU left in Kharkov would be substantially less that that.