MELBOURNE, Australia — The Philippines has taken delivery of the first of 16 Polish-built S-70i Black Hawk transport helicopters it has on order, with another due to arrive in the next month.

A chartered Ukrainian Antonov An-124 transport aircraft delivered five helicopters to Clark Air Base north of the Philippine capital Manila, according to the government news agency.

It added that the Antonov had arrived on Nov. 9 after departing from Rzeszow-Jasionka Airport in Poland two days earlier.

A sixth Black Hawk is being transported by sea and will arrive in the Philippines in early December, according to the country’s Department of National Defense, or DND. The department added that the helicopter is being shipped by sea as the Antonov could only carry five helicopters in its cargo hold.

The remaining ten helicopters will be delivered in 2021.

The helicopters are manufactured by Poland’s PZL Mielec, a subsidiary of Lockheed Martin which had also previously acquired Sikorsky, the original manufacturer of the Black Hawk.

The Philippines acquired the helicopters under a government-to-government deal with Poland, signing a contract worth $241 million in 2019. The Black Hawks are being bought under the U.S. ally’s five-year Horizon 2 modernization program, which will run from 2018-2022.

Transport helicopters are a vital part of the Philippine armed forces. The country is an archipelagic nation made up of over 7,000 islands and has to contend with a number of ongoing insurgencies as well as regular natural disasters, with helicopters frequently used to transport troops and equipment as well as conducting relief operations.

The country seeks to purchase Bell UH-1 utility helicopters recently retired by South Korea, and has also taken delivery of six Brazilian-built Embraer A-29B Tucano counterinsurgency aircraft in mid-October.