One of the European countries sent an air defense system to Ukraine, which did not work in the end, so we had to change it "again and again", Ukrainian President Volodymyr Zelenskyy said on Wednesday, without specifying the country. 

"We have great solutions for Patriots systems, but we do not have them yet,"he added, and noted the Ukrainian military had been training in the United States for the use of the systems. 

"Ukraine needs 20 Patriot systems to protect itself from Russian missiles, and even this may not be enough, because no country in the world has been attacked with so many ballistic missiles," Zelenskyy said.