The U.S. Congress has received notification of Foreign Military Sales requests that if approved would be carry a combined total of more than $1 billion.

According to the U.S. Defense Security Cooperation Agency, which brokers FMS deals, four countries are involved: Greece, the Sultanate of Brunei, Estonia and Brazil.

The proposed sales have passed muster with the U.S. State Department and would "contribute to the foreign policy and national security of the United States."

Greece, a member of NATO, is seeking the possible sale of two P-3B Orion maritime patrol aircraft, overhaul and upgrade of as many as five more, together with the supply of associated equipment, parts, training and logistical support.

The mid-life overhauls and upgrades would include new flight avionics and would extend the aircraft's life by 15,000 flight hours.

The proposed sale, if approved, would be worth an estimated $500 million.

"The proposed sale for overhaul and upgrade would allow the Hellenic Navy to resume operations of its P-3B aircraft for land-based maritime patrol and reconnaissance, surveillance and protection of areas of national interest," DSCA said.

Lockheed Martin would be the principal contractor.

U.S. government and contractor representatives would be required to make multiple trips to Greece over a seven-year period for delivery, system checkout, training, and program reviews.

The Sultanate of Brunei is seeking the purchase of one for C-130J aircraft and associated equipment, parts, training and logistical support for an estimated cost of $343 million.

Included in the proposed package are six AE2100D3 turboprop engines, communication equipment, spare and repair parts, support and test equipment, publications and technical documentation, personnel training and training equipment and logistics support.

DSCA said the sultanate would use the aircraft for maritime patrol, search and rescue, humanitarian aid and disaster relief missions.

Lockheed Martin would be the principal contractor.

Estonia's request, although relatively small in dollar value compared to the others presented to Congress, is the most notable as it involves weaponry and comes at a time of tension in Eastern Europe over Russia's annexation of the Crimea region of Ukraine and threat to the eastern part of that country.

Estonia is a Baltic state. Its regular military force, including conscripts, is less than 6,000.

Estonia, which like Ukraine was once part of the Soviet Union, has requested 350 Javelin guided anti-tank missiles.

The entire sales request, worth $55 million, is for the missiles, 120 command launch units with integrated day/thermal sight, 102 battery coolant units, 16 enhanced performance basic skills trainers, and 102 missile simulation rounds.

Spare and repair parts, rechargeable and non-rechargeable batteries, battery chargers and dischargers and support equipment are also included.

"The proposed sale will improve Estonia's capability to meet current and future threats and provide greater security for its critical infrastructure," Congress was told. "Estonia will use the enhanced capability to strengthen its homeland defense."

Brazil, meanwhile, wants to buy follow-on support and equipment for S-70B helicopters for a period of three years.

The $150 million deal would include the supply of a tactical operations flight trainer.

The S-70 is manufactured by Sikorsky Aircraft. It is a medium transport/utility aircraft originally developed for the U.S. Army.