Brendan Vaughan, the British man thought to have been killed in Nigeria by an Islamic extremist group, was "likely to have been murdered in cold blood", the Foreign Secretary said.
William Hague added that the UK had "worked closely" with Nigeria over the last few weeks, and expressed his thanks to the Nigerian authorities.
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A top temperature today of 13 Celsius (55F).
Mr Trump tweeted that Mr McMaster has done "an outstanding job & will always remain my friend." He said MrBolton will take over on April 9.
The committee wants a more stringent interpretation of air quality laws and for noise estimates to reflect a range of possible flight paths.