The US and UK say air strikes will not be enough to stop Islamic State militants seizing the key Syrian border town of Kobane.
Washington says it is doing everything it can from the air, but that there are limits to what bombing can achieve.
IS fighters reportedly entered two further districts of Kobane overnight, close to the border with Turkey.
Three weeks of fighting in the area have forced over 160 000 refugees across the border into Turkey.
Meanwhile, UK foreign secretary Philip Hammond has given the first official indication that four terror arrests in London this week are thought to be connected to an IS-related plot.
IN: "ISIL...
OUT: ...only one."
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