It is the military version of the Britten-Norman Islander, developed for roles such as utility transport, casualty evacuation, counter-insurgency and light attack, forward air control, patrol and reconnaissance.

Compared to earlier Defenders, it has a stretched fuselage, the enlarged wing from the Trislander, a new nose structure capable of accommodating an EO/IR sensor and radar, and an increased payload.

[3] The FBI deployed one Defender for electronic aerial surveillance on the Branch Davidians' compound during the siege of Waco in 1993.

[7] In 1996, the Royal Cambodian Air Force deployed its three BN-2 Defenders in support of the dry season offensive against Khmer Rouge insurgents.

[9] In January 2004, the British Army placed an urgent order for four BN-2T-4S Defender 4000 aircraft designated the AL Mk 1 for ISTAR missions in Iraq.

[10] The Mk 1 was fitted with a Wescam MX-15 Electro-Optical Infrared (EO/IR) turret under the nose, cabin-mounted cameras, COMINT and C2 equipment.

[10] In June 2009, the Defender's deployment to Iraq ended with 651 Squadron serving continuously since October 2004 during which time it had provided over 8,000 hours in support of UK Forces.

[10] From January to February 2010, the Defender was trialled in the Middle East with a Counter-IED capability for potential use in Afghanistan.