Four NATO soldiers were killed in two separate incidents in restive eastern Afghanistan on Tuesday, the military alliance said in a statement. "Three International Security Assistance Force (ISAF) service members died following an improvised explosive device (IED) attack in eastern Afghanistan today," said a statement issued by NATO- led ISAF. According to the statement, another ISAF service member was killed in an insurgent attack. The brief statement did not reveal the nationalities of the victims, saying it is ISAF policy to defer casualty identification procedures to the relevant national authorities.