He (POTUS) said so a couple of times on Twitter and in a press conference, IIRC. I believe him. He said they were looking at using it. He also tweeted that all the migrants who entered the country shouldn't get too comfy because they were all going to be deported, "as soon as our deportation force is up to full strength", I paraphrase but that was the gist of it.
Together I read that as a very likely plan to use military for deportation of illegals etc.
Try Trump Twitter archive to find the relevant tweets over the past 1-2 weeks.