HUNTSVILLE, Ala. — After years of laboring over details of a complex air and missile defense procurement deal, Poland signed a letter of offer and acceptance on March 28 with the U.S. government to buy Raytheon’s medium-range Patriot system currently in use by the U.S. Army.

According to a source with knowledge of the deal, Poland will buy — for what it’s calling its Wisla program — two Patriot Configuration 3+ batteries, the latest version of the system. There are two fire units per battery, so Raytheon will deliver four fire units total.

The first systems will also have Northrop Grumman’s still-in-development Integrated Air and Missile Defense Battle Command System, or IBCS, and the Lockheed Martin-made Patriot Advanced Capability-3 Missile Segment Enhancement missiles.

The source said delivery is expected in 2022.

At a time of dramatic change in leadership in Poland’s Ministry of Defence, the new guard — having just recently come aboard following the ousting of former Defence Minister Antoni Macierewicz and many of those under him — has brought the complex deal across the finish line.

There were many times where those following the possible procurement thought it would fall through. Poland first selected Patriot in 2014, but with a change in government, the new president wanted to take another look at the options available for a medium-range system.

The government ultimately settled on Patriot, but caught industry off guard when it said it wanted to incorporate Northrop’s IBCS that is in development to be the command-and-control system for the U.S. Army’s future integrated air and missile defense system. IBCS’ initial operational capability is delayed, but Northrop has a way to offer a version of the system for Poland’s Patriots sooner. And a Yockey waiver was granted for Poland to procure the system ahead of the U.S. Army.

The Poles also wanted 360-degree detection capability, which the current Patriot lacks. Poland plans to procure 360-degree radars for the Wisla program later. The U.S. Army is also working toward a 360-degree capability.

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Poland ultimately wants to procure eight batteries, so some of these capabilities will be worked into later phases that will require further agreement between the U.S. and Poland.

The country also slowed the procurement process to go through painstaking offset negotiations to ensure those met legal requirements as well as goals the government had set for the program. The country wanted at least 50 percent domestic industrial participation.

Because of those complicated aspects to the sale, paired by sky-high U.S. State Department cost estimates that were not affordable for Poland, it seemed like an uphill climb to get to the point where both sides were prepared to sign a deal.

Poland closed in on cementing the letter of offer and acceptance last week when it signed an offset agreement. The details were not disclosed and much is classified.

According to Polish reports, the offset totaled just less than 1 billion zlotys (U.S. $295 million) and consisted of 46 offset areas, of which 31 are Northrop- and Raytheon-related and 15 are Lockheed-related. The entire deal, when all phases of the deal are executed, is expected to cost approximately 20 billion zlotys.

“Signing the offset agreement with the Polish MoD sets the stage for the creation of new jobs in the U.S. and Poland and strengthens the trans-Atlantic partnership by fostering the exchange of information and ideas between U.S. and Polish industry,” Pete Bata, Raytheon’s vice president of Poland integrated air and missile defense programs, said at the time of its signing.

Now that the letter is signed, the U.S. government and Poland can begin contract negotiations with Raytheon, Northrop and Lockheed.

“Poland joins the now 15 nation-strong group of countries which trust Patriot to defend their citizens, military and sovereignty,” Wes Kremer, president of Raytheon Integrated Defense Systems, said in a March 28 statement. “Poland’s procurement of Patriot strengthens Trans-Atlantic partnership and security by enabling a common approach to Integrated Air and Missile Defense, and creating jobs in the U.S. and Poland.”

Of NATO members, the U.S., Germany, Greece, the Netherlands and Spain have Patriot, and Romania has signed a letter of offer and agreement for the system. The U.S. State Department has also cleared a possible sale of Patriot to Sweden, which is awaiting congressional approval.

According to Raytheon, the subsequent phase beyond the first two batteries would include the acquisition of additional Patriot fire units, gallium nitride-based 360-degree active electronically scanned array radar and a low-cost interceptor missile called SkyCeptor.

On the Missile Segment Enhancement side, Poland becomes the fifth international customer to sign an agreement to buy the missile. The U.S., Qatar, Japan, Romania and the United Arab Emirates have signed agreements to buy the Missile Segment Enhancement weapon.

“We’re honored to partner with Poland in support of the Wisla Air and Missile Defense system to protect and defend their armed forces, citizens and infrastructure. We also look forward to working with the Polish Armaments Group consortium of companies in support of the agreed to Wisla technology transfer,” Tim Cahill, vice president of Integrated Air and Missile Defense at Lockheed Martin Missiles and Fire Control, said in a March 28 statement.