WARSAW, Poland — The Czech defense ministry has announced its decision to purchase 12 UH-1Y Venom and AH-1Z Viper helicopters with related gear and services from Bell Helicopters under a deal estimated to be worth some 14.5 billion koruna ($623 million).

Under the plan, the new copters will gradually replace the country’s outdated Soviet-designed Mil Mi-24 and Mi-35 helos, the ministry said in a statement. Czech Defense Minister Lubomir Metnar said that the contract is expected to be signed by the end of this year.

“We want to carry out this purchase as soon as possible. Deliveries should begin in 2023,” said Czech Prime Minister Andrej Babis, as quoted in the statement.

As part of the designed contract, the Czech military aims to acquire eight UH-1Y Venom helos and four AH-1Z Viper aircraft.

The Czech Republic has intensified efforts to modernize its armed forces and replace Soviet-made weapons and equipment with new gear, following Russia’s military intervention in Ukraine. Last year, General Ales Opata, the chief of the General Staff of the Czech Armed Forces, unveiled plans by the government to spend 100 billion koruna, $4.3 billion, on what he called the largest military upgrade program in the country’s history.

In 2019, Prague’s defense expenditure is to total 66.7 billion koruna, or $2.8 billion, up roughly 13 percent compared with a year earlier, according to data from the Czech ministry.