With the Russian horse long dead yet still subject to regular beatings, Mueller will now turn his attention to Middle Eastern countries' attempts to influence American elections, according to the Daily Beast, citing three sources familiar with this aspect of the probe who have said that related court filings are set to drop in early 2019. 

While one part of the Mueller team has indicted Russian spies and troll-masters, another cadre has been spending its time focusing on how Middle Eastern countries pushed cash to Washington politicos in an attempt to sway policy under President Trump's administration. Various witnesses affiliated with the Trump campaign have been questioned about their conversations with deeply connected individuals from the United Arab Emirates, Saudi Arabia, and Israel, according to people familiar with the probe. Topics in those meetings ranged from the use of social-media manipulation to help install Trump in the White House to the overthrow of the regime in Iran. -Daily Beast

Cooperating witnesses have reportedly told the special counsel's office information about foreigners' plans to help Trump beat Hillary Clinton in 2016, while Mueller's team has been mulling whether to issue new charges on this side of the investigation according to two sources with knowledge of the probe. 

"If this is going to be unveiled, this would be like the surfacing of the submarine but on the other plank which we haven't seen," said former US attorney Harry Litman. "I guess what Mueller has to date has turned out to be pretty rich and detailed and more than we anticipated. This could turn out to be a rich part of the overall story."