A military personnel of the Singapore Armed Forces prepares for the opening of the Singapore Airshow at Singapore's Changi Exhibition Center, Feb. 16, 2016. The Singapore Airshow kicked off here on Tuesday. The airshow is only for trade professionals from Feb. 16 to 19, while it will be open to the public on Feb. 20 and 21. (Xinhua/Then Chih Wey)

A military personnel of the Singapore Armed Forces prepares for the opening of the Singapore Airshow at Singapore's Changi Exhibition Center, Feb. 16, 2016. The Singapore Airshow kicked off here on Tuesday. The airshow is only for trade professionals from Feb. 16 to 19, while it will be open to the public on Feb. 20 and 21. (Xinhua/Then Chih Wey)

A military personnel of the Singapore Armed Forces prepares for the opening of the Singapore Airshow at Singapore's Changi Exhibition Center, Feb. 16, 2016. The Singapore Airshow kicked off here on Tuesday. The airshow is only for trade professionals from Feb. 16 to 19, while it will be open to the public on Feb. 20 and 21. (Xinhua/Then Chih Wey)

Visitors watch the flying demonstration of an unmanned aerial vehicle (UAV) at the Singapore Technologies booth during the opening of the Singapore Airshow at Singapore's Changi Exhibition Center, Feb. 16, 2016. The Singapore Airshow kicked off here on Tuesday. The airshow is only for trade professionals from Feb. 16 to 19, while it will be open to the public on Feb. 20 and 21. (Xinhua/Then Chih Wey)

A military personnel of the Singapore Armed Forces prepares for the opening of the Singapore Airshow at Singapore's Changi Exhibition Center, Feb. 16, 2016. The Singapore Airshow kicked off here on Tuesday. The airshow is only for trade professionals from Feb. 16 to 19, while it will be open to the public on Feb. 20 and 21. (Xinhua/Then Chih Wey)