The United Nations Mission of Support in East Timor (UNMISET) was established by Security Council resolution 1410 (2002) of 17 May for an initial period of 12 months, starting on 20 May 2002, with the following mandate:

• To provide assistance to core administrative structures critical to the viability and political stability of East Timor;
• To provide interim law enforcement and public security and to assist in the development of a new law enforcement agency in East Timor, the East Timor Police Service (ETPS); and
• To contribute to the maintenance of the external and internal security of East Timor .

The Council also requested UNMISET to give full effect to the following three Programmes of the Mandate Implementation Plan as set out in section III A 3 of the report of the Secretary-General ( S/2002/432 ) of 17 April 2002 :

• Stability, Democracy and Justice;
• Public Security and Law Enforcement; and
• External Security and Border Control.

On 19 May 2003, that mandate was extended for another year, until 20 May 2004, by Security Council resolution 1480 (2003 ).

On 14 May 2004, the Security Council, in its resolution 1543 , again extended the mandate of UNMISET for a period of six months, with a view to subsequently extending the mandate for a further and final period of six months, until 20 May 2005 . It also decided to reduce the size of the mission and revise its tasks, in accordance with the recommendations of the Secretary-General as outlined in his report of 29 April 2004 to include the following elements:

(i) support for the public administration and justice system of Timor-Leste and for justice in the area of serious crimes;

(ii) support to the development of law enforcement in Timor-Leste;

(iii) support for the security and stability of Timor-Leste.

On 16 November 2004, the Security Council, by its resolution 1573 (2004), extended the mandate of UNMISET for a final six months until 20 May 2005 . The Council also decided to maintain UNMISET's tasks, configuration and size, in order to allow the Mission to complete its mandate and consolidate gains made in that country thus far.

On 20 May 2005, UNMISET successfully concluded its mandate in Timor-Leste. It was succeeded by a small follow-on political mission – the United Nations Office in Timor-Leste (UNOTIL), which was established by the Security Council to ensure that the underpinnings of a viable State are firmly in place in that country.