WARSAW (Reuters) - Poland expects to sign a deal worth up to $7.6 billion with U.S. firm Raytheon to buy eight Patriot missile defense systems by the end of the year, Defense Minister Antoni Macierewicz said on Friday.

Poland's Defence Minister Antoni Macierewicz speaks during a news conference in Tallinn, Estonia, March 14, 2017. REUTERS/Ints Kalnins

Warsaw sees the deal as central to a thorough modernization of its armed forces by 2023, in light of what Macierewicz called “growing aggression and a growing threat from the East.”

NATO member Poland has sped up efforts to overhaul its military following Russia’s annexation of Ukraine’s Crimea peninsula in 2014 and in response to Moscow’s renewed military and political assertiveness in the region.

“Those systems allow us to guarantee the security of the Polish state,” Macierewicz told a news conference.

The contract still requires approval from the U.S. Congress, as it involves a purchase of advanced military technology for which special permission must be obtained.

“It’s premature to say that it is all done,” Bill Schmieder, Raytheon’s head for Europe, told the same briefing. “But we have very high hopes that the process will proceed normally.”

The Patriot mobile missile defense interceptors are designed to detect, track and engage unmanned aerial vehicles (UAVs), cruise missiles and short-range or tactical ballistic missiles.

Poland should receive the first of the Patriot systems within two years of signing the contract, Macierewicz said. All of the units would come with the Integrated Battle Command System (IBCS), designed to give commanders a better perspective of their operating environment to make better informed decisions.

Starting with the delivery of the third system, the Patriots will also be equipped with 360-degree surveillance radars.

Poland spends about 2 percent of its gross domestic product on defense, in line with NATO’s target. But some military officials are pressing for more, saying nearly two-thirds of hardware dates from the era when the country was in the Moscow-led Warsaw Pact.

Later on Friday, the Defence Ministry said it had also signed a $523.6 million agreement with Boeing to supply three 737-800 airliners for the use of senior Polish state officials.

Two aircraft will be new and one used. The used aircraft will be delivered this year and the two new airplanes in 2020.