Strange? It's normal.
They called it a "counter trade".
Countertrade is an umbrella term covering a wide range of commercial mechanisms for reciprocal trade. Barter is probably the oldest and best known example, however others, such as offset, buyback, tolling and switch-trading, have also evolved to meet the requirements of a more sophisticated world economy. All of these generally involve the exchange of goods or services to finance purchases, rather than using cash alone. Countertrade, in its various forms, represents 10-15% of world trade (esp. when buying military equipments, between developing countries n developed countries v.v).
Thai May Not Buy Airbus Fleet: