Turkey has signed a government-to-government deal with the United States to buy six Boeing-made CH-47 heavy-lift military transport helicopters, the first such weapons in its inventory, a senior procurement official said over the weekend.

The deal is worth up to $400 million, the official said.

The Defense Security Cooperation Agency, or DSCA, the Pentagon’s body coordinating weapons sales, notified the U.S. Congress of a potential sale of a total of 14 CH-47F heavy-lift helicopters for $1.2 billion in December 2009. Congress gave permission for the sale later that month.

The six CH-47F Chinooks will be the first heavy-lift helicopters in the Turkish Army’s inventory. The deliveries are expected to begin in 2013 and end in 2014, Hürriyet Daily News reported.