The vessels in question will be primary corporations such as GMG and ALG. Along with them will be independents such as Zoners or Freelancers. Their cargo will be primarily Industrial materials that will be vital to future plans the Overwatch is interested in. However, this is not be one convoy and more of a rapid push of many vessels making the journey to our territory. Obviously we for see the Core, Nomads, and Outcasts wanting to stop us at all costs. Given the scarcity of such resources in the Omicrons I imagine that many of our enemies would also rather capture such materials and use them of themselves.