Military analysts determined that more resources were needed to secure population centers, train local troops and ward off insurgent forces.

FORBES: Is Afghanistan a Problem of Capacity or Complexity?

In his first statement to MPs since taking on the new role Philip Hammond said UK troops in Helmand province were having a "tangible impact" on insurgent activity.

BBC: Philip Hammond: Afghanistan progress not 'irreversible'

The group is reportedly considering options such as a gradual pull-out of American troops and a diplomatic push to persuade Iran and Syria to curb the insurgent groups they are thought to encourage.

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