Taiwan's top military official was killed in an air force helicopter crash Thursday morning that also left seven others dead, the Defence Ministry said.

As chief of the general staff, Gen. Shen Yi-ming was responsible for overseeing the island's defence against China, which threatens to use military force to annex what it considers its own territory.

The helicopter was flying from Taipei to the northeastern city of Yilan for a new year's activity when it crashed.

According to the Defence Ministry, 13 people were on the UH-60M Blackhawk helicopter, which took off shortly after 7:50 a.m. local time from Taipei's Songshan air force base on its way to a base in Yilan county on the east coast. Just over 10 minutes later, it dropped from the radar screen and went down in the mountainous, heavily forested Wulai area southeast of the capital.

Shen, 63, had taken over as chief of the general staff in July after serving as commander of Taiwan's air force, which is undergoing a substantial upgrade with the arrival of the most advanced version of the U.S. F-16V fighter.

'Very calm and very stable'

Alexander Huang, a strategic studies professor at Tamkang University in Taiwan who had known Shen for a decade, said he had stood out as a pilot and an officer.

"He was very calm and very stable, and unlike other army guys he was always smiling, so he got a specific leadership style that also made him a popular leader in the entire military," Huang said.

It will likely be months before the cause of the crash is known, but the pilots, both of whom were killed, appeared to have been highly experienced.

"Of course, reasonable people would think in the direction of mechanical failure or maintenance problem, but without proof, you can't say anything," Huang said.

Taiwan's military has operated Blackhawks for decades and in 2010, completed a sale for another 60 UH-Ms from the U.S. for $3.1 billion US. The Blackhawk that crashed was a model dedicated to search and rescue and had been delivered in 2018, according to the ministry.

Rapid reshuffle

The loss of Shen and other high-ranking officials will require a rapid reshuffle of positions, but should have a minimal effect on Taiwan's Jan. 11 elections for president and lawmakers, said Andrew Yang, a former Ministry of National Defence deputy minister for policy who also worked with Shen .

"He was highly respected throughout his career," Yang said.

"I don't think the crash will have a strong impact over the elections but certainly it will affect the armed forces because so many senior officers passed away as a result of this crash,"

Taiwan's ruling Democratic Progressive Party has been strongly critical of China's attempts to increase economic, military and diplomatic pressure and incumbent President Tsai Ing-wen appears on track to win a second term over her more pro-China opponent, Han Kuo-yu of the main opposition Nationalists.