Story highlights The killing comes a week after Haji Mali Khan was captured

Officials believe the Haqqanis were involved in the Rabbani assassination

NATO-led forces have conducted hundreds of operations against the network this year

A week after the senior Haqqani network leader in Afghanistan was captured, a coalition airstrike killed one of his associates, NATO's International Security Assistance Force said on Wednesday.

Dilawar, known by one name, died in the Musa Khel district of eastern Afghanistan's Khost province on Tuesday in what ISAF called "another significant milestone in the disruption of the Haqqani network." Two other militants were killed in what was an Afghan-coalition operation, ISAF said.

Dilawar was a "senior Haqqani leader" and "a principal subordinate" to Haji Mali Khan, whose capture in Paktia province last Tuesday was hailed as a blow against the network, widely regarded as one of the most effective militant groups in Afghanistan.

Western officials believe the Haqqanis were involved in the assassination last month of Burhanuddin Rabbani, the chairman of Afghanistan's High Peace Council, and a June attack on the Intercontinental Hotel in Kabul.

Dilawar planned attacks with Mali Khan, including an ambush on Afghan forces in Paktia last month.

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"Dilawar operated along the Afghanistan-Pakistan border, between the Khost and Paktia provinces, where he actively coordinated numerous attacks against Afghan forces and facilitated the movement of weapons. Dilawar also facilitated the movement of foreign fighters and was associated with both al Qaeda and the Islamic Movement of Uzbekistan," ISAF said.

ISAF said security forces have conducted more than 530 operations this year "to disrupt Haqqani network activities in eastern Afghanistan. It said the effort led to the deaths of 20 network leaders and the capture of more than 1,400 suspected Haqqani insurgents.

Khan is the uncle of Siraj and Badruddin Haqqani -- the brothers who lead the network -- and worked directly under Siraj, managing bases and overseeing operations in Afghanistan and Pakistan.

The network was founded by Siraj Haqqani's father with Pakistani backing to fight against the Soviet occupation of Afghanistan. Today, the group is believed to maintain ties with Pakistan's Inter-Services Intelligence agency.