<sod >"Thus, we cannot rule out technical assistance from Russian personnel in operating the systems," she said, adding: "it is extremely important that an investigation be commenced immediately." Earlier on Friday, White House spokesman Josh Earnest said it "is critical that there be a full, credible, and unimpeded international investigation as quickly as possible".< eod>< sod > "Thus, we cannot rule out technical assistance from Russian personnel in operating the systems," she said, adding: "it is extremely important that an investigation be commenced immediately." At the meeting called by Britain, UK's ambassador Sir Mark Lyall Grant said "searching questions" had to be asked about Russia's links with armed separatists and called for Moscow to issue an "unequivocal condemnation" of their actions.< eod>