(Reuters) -Kyiv has agreed with two American firms to jointly manufacture vital 155mm artillery shells in Ukraine, a Ukrainian minister said on Thursday, although production will not start for at least two years. Demand for 155mm rounds soared following Russia’s full-scale invasion of Ukraine in 2022. The U.S. and allies have sent Kyiv more than 2 million and are trying, with limited success, to increase production to replenish stocks. “We have agreements with two leading American companies to jointly produce, in Ukraine, 155-calibre ammunition,” Oleksandr Kamyshin, minister for strategic indu…