White House adviser Tony Blinken says there is evidence that Russia is preparing to deliver more powerful rocket launchers to separatist rebels in eastern Ukraine.
Western powers have accused pro-Russian rebels in the area of shooting down Malaysia Airlines flight MH17 with a rocket.
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A suspected drunk driver ploughed into a crowd during Mardi Gras celebrations in the southern US city.
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.