President Hamid Karzai's office said the two men discussed issues of mutual interest, including the possibility of Afghan students studying engineering and medicine in Bulgaria. Plevneliev invited Karzai to pay an official visit to Bulgaria and the Afghan president accepted, the statement said, though no date was announced. Bulgaria has 614 soldiers, army instructors and military doctors in NATO's US-led International Security Assistance Force (ISAF), which plans to end combat operations in 2014. Bulgaria will withdraw 10 military doctors from a Spanish field hospital in Afghanistan's third city of Herat by the end of this year, while 257 soldiers patrolling Kabul airport will follow suit in early 2013. A 347-strong troop contingent guarding the airport in the southern city of Kandahar will be the last to pull out by the official ISAF deadline. Bulgaria has not suffered any casualties in Afghanistan so far, apart from a French Foreign Legion army trainer killed along with three other French troops by a renegade Afghan soldier inside their base on January 20.