The US has added Libya, Somalia and Yemen to a watchlist of countries linked to visa-waiver status.Anyone with dual citizenship from these countries or who had visited one last five years now needs to undergo a more rigourous regular visa application process before entering the US.The addition follows rules introduced last year covering Iran, Iraq, Sudan or Syria. Those changes to the visa-waiver program come after the terrorist attacks in Paris on Nov. 13 that killed 130 people and wounded 368.The Obama administration has suggested limited exemptions to those who have to travel to any of the seven countries as diplomats or for military service, as well as humanitarian workers or journalists.However, critics have said this would endanger national security.