As a somewhat humorous aside, I would caution the DHS on any planned "joint operations" within Zones IV & VI.
An article discusses attempts to debunk the rumor. It sites Snopes.com's take on this rumor as part of the debunking justification. It is widely believed (and with good reason) that Snopes.com is liberal/progressive in its leanings. Assuming that to be the case, and I do, one should be wary of Snopes.com for anything relating to this administration. For things apolitical it seems fairly reliable. Below the main referenced article I have included a "take" on Snopes.com and its potential bias.
For the article discussing the debunking of Russians operating on US soil, Click Here.
For the "take" on Snopes.com, Click Here.