Taiwan has submitted a formal request for the purchase of 66 F-16V fighter jets from the United States to counter a military buildup by China, with Deputy Minister of National Defense Shen Yi-ming admitting they were needed “to counter current enemy threats”.

Media reports suggest that a letter of request was submitted for the NT$400 billion (US$13 billion) package on February 27, though it was only confirmed Thursday. The cost would include the training of pilots and servicing of the aircraft.

“We made the request to purchase (fighter jets) because China has been increasing its military strength and we are starting to have an imbalance of power in our air defense capabilities,” Shen said.

There has been speculation for some time that Taiwan would phase out its ageing fighter fleet, mainly Dassault Mirage F-2000-5 and AIDC F-CK-1 jets, however national defense spokesman Major General Chen Chung said “the plan for the new fighter jets is about enhancing air defense capabilities, not replacing existing jets”.

Reports suggest that the numbers and type of aircraft being procured are not fixed, as the Pentagon has been asked to advise on the mix that would be required to effectively defend the island’s airspace. The defense ministry said the price would be negotiated once the US had responded.

Some media outlets have linked the deal with rumored plans for a visit by Prime Minister Tsai Ing-wen to the US ahead of the presidential election in 2020, but the defense ministry denied there was any connection. China has not commented on the planes order.

While the procurement is being sorted, Taiwan continues to upgrade its existing F-16A/Bs to a F-16V configuration, but the work is behind schedule.  The air force is reportedly liaising with manufacturer Lockheed Martin through the American Institute in Taiwan (AIT) — Washington’s de-facto embassy in Taiwan — according to the Central News Agency of Taiwan.

The F-16V carries the AN/APG-83 radar, which offers an improved detection range and better fire control than earlier models. It can also be equipped with AIM-9X missiles linked to a helmet-mounted cueing system.

AIT spokeswoman Amanda Mansour said that it is the policy of the US government not to comment on proposed defense sales or transfers until the US Congress has been formally notified.

“Without speaking to any specific cases, we can say that under longstanding US policy, US arms sales to Taiwan are guided by the Taiwan Relations Act and based on an assessment of Taiwan’s defense needs,” Mansour said.