and limited domestic capability. Development and modernization of China's aviation industry occurred alongside the J-10; the program was an early Chinese user of digital design, modelling, and testing including computer-aided design (CAD) and computational fluid dynamics. The J-10 was the first Chinese aircraft to make major use of computer-aided design (CAD) for its structural design, allowing the detailed design to be completed in 1994. The hydraulics system was tested with physical models because of limited digital modelling capabilities. The first J-10 was assembled in June 1997. Lei Qiang flew the first flight on 23 March 1998; Lei was chosen for his experience with modern, foreign, third-generation aircraft. PLA training units received the J-10 ahead of schedule starting in 2003. Weapons tests occurred in the fall of that year. The design was finalized in 2004. Rumors of crashes during flight testing were actually mishaps related to the AL-31 engine. The J-10 became operational in 2006. It was officially unveiled by the Chinese government in January 2007, when photographs were published by Xinhua News Agency. The Siberian Aeronautical Research Institute (SibNIA) from Russia was involved in the program by 2016. According to SibNIA, it was only observing and instructing as "scientific guides". According to the images posted by China National Radio of a PLAAF live-firing exercise at an unspecified location in May 2021, J-10C Vigorous Dragons were equipped with distinctive exhaust nozzles of the WS-10B Taihang turbofan engine. This marks the first time the WS-10 has been officially seen on an operational J-10. Disputed origins In 1988 Israel's defense minister denied a report by the Sunday Times of London that Israel and China had agreed to develop a fighter derived from the IAI Lavi, a project based on the F-16. In 2006, Russia's SibNIA engineers believed that the J-10 was "more or less a version" of the Lavi, incorporating "a melting pot of foreign technology and acquired design methods... but there are a number of other pieces of other aircraft or technologies that are part of the configuration that they have acquired from different sources." In 2008, Janes claimed that the J-10 benefited from technical information from the Israeli project, citing senior Russian engineers who said they had heard this from Chinese colleagues. The Chinese assert J-10's features claimed to be from the Lavi are from the manufacturer's own previous aircraft design, for example attributing the J-10's Lavi-like double canard configuration to