 Due to the poor response to the demand for the surrender of weapons , the deadline was extended several times until a date of 8 July was fixed . On 17 May , courts @-@ martial were established to try those that were arrested in possession of weapons , and those found guilty were immediately executed by firing squad . The precedent for this brutal repressive measure against Serbs had already been established by the Germans . It was clear from the outset that the NDH weapons laws were not being enforced as strictly against Croats as they were against Serbs . <unk> the border between eastern Herzegovina and Montenegro was considered a high priority due to concerns that the Montenegrin <unk> Party had revived Montenegrin claims to parts of the NDH that had been promised to the Kingdom of Montenegro in the 1915 Treaty of London . 
