KYIV, Aug. 28 – Ukraine seeks to acquire an air defense system from the U.S. in a deal that may be worth over $2.25 billion, Valeriy Chaly, the Ukrainian Ambassador to the U.S., said Tuesday.

The deal was discussed earlier this year between President Petro Poroshenko and U.S. President Donald Trump, and most recently with U.S. National Security Adviser John Bolton during his trip to Kyiv.

Ukraine also seeks to buy more counter battery radars that pinpoint enemy artillery and have proven their efficiency on battle field. Ukraine also wants to buy more drones to improve field communications between its troops.

"Our next needs, in my opinion, [are for equipment covering] maritime space and airspace without which we are simply not able to provide defense of the country," Chaly said in an interview with Novoye Vremya Radio.

The request to acquire the air defense system signals a major shift in military strategy as the country has so far relied on mostly Russian-made anti-aircraft systems to defend its airspace.

The deal would greatly improve the Ukrainian ability to defend itself against Russia’s overwhelmingly superior air force.

Russia hasn’t used its air force in the military conflict over Donetsk and Luhansk, but has been recently using its naval vessels and aircraft to harass and disrupt traffic of Ukrainian commercial ships in the Sea of Azov.

Russia detained more than 150 vessels heading for Ukrainian ports in the Sea of Azov over the past several months, according to Ukraine's State Border Guard Service.

Chaly said Ukraine seeks to acquire three anti-aircraft units from the U.S. with each costing $750 million. He did not elaborate further, saying the information is top secret.

Poland in March signed an agreement to acquire U.S. Raytheon Co’s Patriot missile defense system for $4.75 billion, the largest arms procurement deal in its history. The deal is for the delivery in 2022 of two Patriot batteries manufactured by Raytheon, each with two fire units.

The US in March formally approved the sale of Javelin anti-tank missile systems to Ukraine that includes 210 missiles and 37 launchers by contractors Raytheon and Lockheed Martin at a price of around $47 million.

Washington had been cautious in the past about escalating the conflict by providing advanced "lethal" weaponry to Kyiv due to the risk of heightening tensions with Moscow.

But in December 2017 the US announced it would provide Ukraine with "enhanced defensive capabilities" as the war in the east drags on, having claimed more than 10,000 lives since 2014. (tl/ez)