The new American Secretary of State John Kerry has arrived in the UK for his first official overseas visit.
He will visit nine nations over the course of an 11-day trip on which he is expected to focus on the conflicts in Syria, Mali and Afghanistan.
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The singer had been tweeting in support of migrants when she was bombarded with abusive messages.
Ministers are reportedly considering plans in a bid to lower inward migration.
In a tweet on Saturday, the US president didn't give a reason for his absence but said he wished"everyone well and have a great evening".