WARSAW, Poland ― Croatia’s Defence Ministry says it has received four offers in its tender to acquire 18 fighter jets. The bids were placed by the United States, Israel, Sweden and Greece.

The Croatian government has been mulling plans to purchase new or secondhand Lockheed Martin F-16s, offered by the U.S., Israel and Greece, or buy Saab JAS-39 Gripens from Sweden.

“Following the opening of the bids, a detailed evaluation and validation process of the bids by the Expert Team will take place within a period of about two months,” the ministry said in a statement. “The key parameters in the selection procedure, aside from the characteristics and capabilities of the aircraft, will comprise three segments: intergovernmental contract, price, and the business-economic cooperation package.”

Croatia aims to replace its outdated, Soviet-designed Mikoyan MiG-21s. Under the plan, the first fighters are to be delivered to the Croatian Air Force by late 2020.

Last July, the ministry submitted requests for proposals to potential bidders, including South Korea, which was expected to offer its FA-50 aircraft, but Seoul did not place a bid in the tender, according to the ministry.

In addition to Croatia, other countries in the region that are pursuing programs to replace their aircraft include Poland, Romania, the Czech Republic, Slovakia and Bulgaria.