The Taliban takeover of Afghanistan has “heartened and emboldened” Islamic extremists and the UK is vigilant to the increased terror threats, Britain’s domestic intelligence chief said on Friday. Talking to the BBC’s Today programme on the eve of the 20th anniversary of the 9/11 terrorist attacks, Ken McCallum, director-general of the MI5 intelligence agency, also said that the threat of terrorism in the UK remains “real and enduring.” “There is no doubt that events in Afghanistan will have heartened and emboldened some of those extremists,” he said. The UK government has pledged to judge the Taliban “by their actions,” but McCallum said UK security services would plan for the chance that “more risk progressively may flow our way.” While large-scale, “more directed plots” from terrorist organisations take time to organise and carry out, the MI5 chief said “psychological boosts” for would-be terrorists could happen “overnight.” “We do face a consistent …