(Reuters) – U.S. President Barack Obama and British Prime Minister David Cameron vowed a united front on Wednesday against the threat posed by Islamist extremists and their “distorted ideology.”

In a joint opinion article that appeared in Thursday’s Times of London newspaper and released on Wednesday night in Washington, Obama and Cameron outlined the principles of the U.S.-British alliance ahead of two days of White House meetings.

The two leaders are to have a working dinner on Thursday night and hold more talks on Friday.

Obama and Cameron, noting the Paris attacks last week against a satirical newspaper, said extremists would not muzzle freedom of speech.

“Whether we are facing lone fanatics or terrorist organisations such as al-Qaeda, Islamic State or Boko Haram, we will not be cowed by extremists. We will defeat these barbaric killers and their distorted ideology,” the leaders wrote.

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