One of the three Nimrods on strength was retired at the end of November 2009 with the other two remaining in service until June 2011. The Nimrods were replaced by three Boeing RC-135W Rivet Joint aircraft. In January 2011 personnel from 51 Squadron began training at Offutt Air Force Base in the US for conversion to the RC-135. Crews were to be deployed on joint missions with the USAF 343rd Reconnaissance Squadron until the new aircraft became available. The first RC135W (ZZ664) was delivered to the Royal Air Force on 12 November 2013, and entered operational service in 2014, taking part in Operation Shader against ISIL in Iraq and Syria.