It will make for a great Ad for the Dems...
A cut of Trump leading the cheer that Mexico will pay for the wall and then a cut of Trump taking money from the military to pay for the wall.
That the military is going to pay for the wall doesn't mean that Mexico is not going to. It looks like Trump's plan all along was to get the big $$$ for the military (he did) and then he can have the wall too, as a Defense item.
As for Mexico,Trump is likely planning to make them pay involuntarily, through remittances$$ control, welfare $ control over $$ cut to Mexicans, repeal of birthright citizenship, etc. Nothing to it, and nothing Mexico can do to stop it.
Next, I think Trump will bill Mexico for reparations of hundreds of Billions$$ of US dollars lost in remittances$$ over the years.
Funny how the Trump haters still haven't figured out the Trump MO - that brought him to the top of the real estate world + the POTUS.