Boeing said on Tuesday it has delivered the Qatar Emiri Air Force's fourth C-17 Globemaster as part of a deal signed in 2008.
The delivery reflects Qatar's agreement with the US government to acquire two additional C-17s, which brings the Qatar Emiri Air Force (QEAF) fleet of the world's most advanced airlifters to a total of four.
Qatar received its third airlifter earlier this year.
Qatar's C-17s earlier this year supported the NATO-led operation in Libya and provided relief for drought victims in Kenya.
In early 2010, QEAF C-17s delivered humanitarian aid to Haiti and Chile following devastating earthquakes.
"The C-17's reliability, along with its unique strategic and tactical capabilities, has expanded our reach and ability to support missions worldwide on a moment's notice," said Brig Gen Ahmed Al-Malki, head of Qatar's airlift committee.
"Doubling our fleet strengthens our ability to support humanitarian, disaster-relief and peacekeeping missions."
Bob Ciesla, Boeing vice president, Airlift and C-17 programme manager, added: "We are proud to be their partner and appreciate their confidence in the world's most reliable airlifter."
Qatar, the first Middle East nation to order the C-17, signed an agreement with Boeing in July 2008 for two advanced airlifters and associated equipment and services, with options for two additional aircraft. Boeing delivered Qatar's first two C-17s in 2009.
Boeing has delivered 249 C-17s worldwide, including 218 to the US Air Force active duty, Guard and Reserve units.
A total of 31 C-17s have been delivered to Australia, Canada, Qatar, the UAE, the UK and the 12-member Strategic Airlift Capability initiative of NATO and Partnership for Peace nations. India has 10 C-17s on order for delivery in 2013 and 2014.
Headquartered in St Louis, Boeing Defence, Space & Security is a $32bn business with 61,000 employees worldwide.