In this paper, the position control of multiple unmanned aerial vehicles, acting as cooperative jammers, is proposed to improve the security level of a legitimate ground transmission, where a precoder is designed to nullify the jamming signals at the legitimate receiver. In this scenario, the maximisation of the weighted secrecy coverage, which measures the efficiency of cooperative jamming over a confined region, is addressed by following a multi armed bandit-based algorithm. The results show that our proposal converges to the one obtained by exhaustive search, and it shows significant improvent over a projected gradient-descent benchmark, while offering a shorter running-time. It was also shown that the employment of only two UAVs joint with the precoder leads to significant advantages in terms of secrecy performance.