US officials wiretapped Paul Manafort way back in2014, and that continued during the campaign and may have included conversation he had with Trump. Update!

Courtesy of CNN:

US investigators wiretapped former Trump campaign chairman Paul Manafort under secret court orders before and after the election, sources tell CNN, an extraordinary step involving a high-ranking campaign official now at the center of the Russia meddling probe. 

The government snooping continued into early this year, including a period when Manafort was known to talk to President Donald Trump. 

Some of the intelligence collected includes communications that sparked concerns among investigators that Manafort had encouraged the Russians to help with the campaign, according to three sources familiar with the investigation. Two of these sources, however, cautioned that the evidence is not conclusive.

Special counsel Robert Mueller's team, which is leading the investigation into Russia's involvement in the election, has been provided details of these communications. 

A secret order authorized by the court that handles the Foreign Intelligence Surveillance Act (FISA) began after Manafort became the subject of an FBI investigation that began in 2014. It centered on work done by a group of Washington consulting firms for Ukraine's former ruling party, the sources told CNN.

The surveillance was discontinued at one point and the restarted as the FBI launched its investigation into the Trump campaign's ties to Russia.

The fact that this surveillance has been going on for so long, and that Mueller has access to every recording should make it almost impossible for Trump to sleep at night.

And apparently that might be part of Mueller's strategy.

Courtesy of the New York Times:  

7The moves against Mr. Manafort are just a glimpse of the aggressive tactics used by Mr. Mueller and his team of prosecutors in the four months since taking over the Justice Department’s investigation into Russia’s attempts to disrupt last year’s election, according to lawyers, witnesses and American officials who have described the approach. Dispensing with the plodding pace typical of many white-collar investigations, Mr. Mueller’s team has used what some describe as shock-and-awe tactics to intimidate witnesses and potential targets of the inquiry. 

Mr. Mueller has obtained a flurry of subpoenas to compel witnesses to testify before a grand jury, lawyers and witnesses say, sometimes before his prosecutors have taken the customary first step of interviewing them. One witness was called before the grand jury less than a month after his name surfaced in news accounts. The special counsel even took the unusual step of obtaining a subpoena for one of Mr. Manafort’s former lawyers, claiming an exception to the rule that shields attorney-client discussions from scrutiny. 

“They are setting a tone. It’s important early on to strike terror in the hearts of people in Washington, or else you will be rolled,” said Solomon L. Wisenberg, who was deputy independent counsel in the investigation that led to the impeachment trial of President Bill Clinton in 1999. “You want people saying to themselves, ‘Man, I had better tell these guys the truth.’”

Keep in mind that Mueller could not get these warrants or have the leeway to use these tactics, if he was not in possession of evidence that convinces judges to hand out these subpoenas like Halloween candy to his team.

Clearly Mueller is preparing to drop the hammer.

Update: Hammer is about to drop:  

The developments indicate that Mueller's investigation "is nearing the litigation stage," said Brookings Institution fellows and legal experts Benjamin Wittes and Susan Hennessey. 

"Combined with a flurry of stories about subpoenas, grand-jury appearances and other activity, it's reasonable to expect that Mueller is moving forward on a number of different fronts and is getting close to entering a litigation phase," wrote Wittes and Hennessey, a former attorney for the National Security Agency.

That sound you hear is the tightening of the noose.