BERLIN, March 27 (Reuters) - Germany aims to purchase up to 28 self-propelled howitzers to replace weapons rushed to Ukraine out of army stocks last year, according to a budget draft seen by Reuters on Monday. The document said the ministry intended to soon trigger options for the procurement of 12 additional howitzers in order to replace all the weapons handed over to Ukraine and to also make up for spare parts supplied to Kyiv. See here for a complete list of exchanges and delays