By John Irish PARIS (Reuters) -Ukraine has bought six Caesar howitzers, France’s defence minister said on Thursday, adding that Paris would send 50 precision-guided missiles a month to Kyiv to aid its fight against Russia’s invasion. Speaking to France Inter radio, Sebastien Lecornu said Caesar manufacturer Nexter had managed to halve the production time of the howitzer to 15 months meaning that some 78 units would be available this year. In Ukraine’s first purchase of French-made weapons since the start of the war, Lecornu said Kyiv had bought six for between 3 million and 4 million euros ($3…