From 1996 to 2006 the country was in civil war against Maoist rebels who strove to overthrow the constitutional monarchy and establish a republic. Their attacks increased since the massacre of the Royal Family in 2001. This development led to the need for armed helicopters. Several types of aircraft have entered service since: MI-17s, M28 Skytruck, HAL Lancer and HAL Dhruv. The UK has delivered two Britten-Norman Islanders and two MI-17s free of charge. China decided to supply an MA-60 (a Y-7 derivative). Nepal has also purchased HAL Cheetah and HAL Chetak helicopters.