Britain has withdrawn its military trainers working with security forces in Pakistan at the request of the Pak government. The trainers, numbering about 20, were working with Pakistan's frontier constabulary – a paramilitary force on the front line of the fight against the Taliban and al-Qaeda. British Defence Ministry said the step has been taken due to security concerns, but added that the withdrawal was temporary. United States has already had to bring home more than 100 military trainers. Relations between Pakistan and its western allies have been under severe strain since US special forces killed Osama Bin Laden on May 2.