Diplomats and employees of international organisations, e.g. the UN are granted category G visas if their visit to the US is in pursuit of official duties.
Officials and employees who work for NATO in the US, need NATO visas. There are different types of G visas. Which one you will need as an official depends upon your purpose of travel to the US.
International organization officials and employees requiring visas include:
G1: representatives of foreign governments who are living and working in the US
G2: representatives of recognised governments travelling temporarily to the US to attend meetings of an international organization
G3: representatives of non-recognised and non-member governments
G4: individuals who are travelling to the US for an appointment with an international organization (including the UN)
G5: attendants, servants and personal employees of the visa holders above
G1, G2, G3 and G4 visas also include immediate family members of the visa holders.
