Russian expert James Nixey told ITV News that he does not think the meeting between Russian President Putin and Prime Minister Cameron will "result in a substantial change in position."
He says there is still a "fundamental divergence of values" on the issue, and he does not think "one pre-judo meeting" will accomplish.
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A police raid uncovered what is believed to be cocaine that had been stashed in nappies, and 40 cannabis plants.
The prince attended the rugby match in his role as patron of the Invictus Games Foundation, the official charity for this year's game.
The prime minister pitched her comments firmly towards unionists in her first campaign visit to Scotland ahead of the general election.