Prime Minister Boris Johnson has been accused of adopting a “more casual” approach to Britain’s national security as lawmakers warned the Whitehall machine was unable to cope with more than one major crisis at a time. The Joint Committee on National Security Strategy—made up of senior MPs and peers—said the fall of Afghanistan had shown the current system was “inadequate to the task.” However, it said that reforms to the National Security Council (NSC) meant the prime minister would slash the time he spent leading its meetings by around two-thirds. In a highly critical report, the committee said the lack of preparation for the withdrawal of international forces from Afghanistan could “only be described as a systemic failure.” The NSC was originally established in 2010 by David Cameron with weekly meetings bringing together senior ministers and defence and intelligence chiefs chaired by the prime minister. However, the committee said a …