Qatar’s air force will receive 36 Boeing F-15QA fighters under a $6.17 billion deal announced by the US Department of Defense on 22 December.

The order comes after the DOD notified Congress in November 2016 that Qatar could buy up to 72 F-15QAs and associated equipment worth $21 billion over the long-term.

The contract requires all deliveries before 2023, the DOD’s announcement says.

Amid growing tensions with regional neighbours, the F-15QA contract is part of a massive tactical fighter build-up by the Gulf state.

Last September, Qatar announced a deal to buy 36 Eurofighter Typhoons worth $6.7 billion. Qatar also ordered 36 Dassault Rafales in March 2016 in a deal valued at $7 billion.

The DOD notice in November 2016 said the F-15QA deal would require 150 contractors to be based in Qatar, along with 25 military support personnel.