Mueller targets the White House, another Russian threat looms, and Trump flips on FISA: The latest in the Russia probe

Thomson Reuters

Robert Mueller.

This week brought more drama and a slew of revelations in the Russia investigation. President Donald Trump set lawmakers scrambling when he blasted out an early-morning tweet about a controversial surveillance law that he said was used to "so badly surveil and abuse" the Trump campaign along with the "discredited and phony Dossier."

That dossier, an explosive collection of memos alleging ties between Trump and Russia, also took center stage when Democratic Sen. Dianne Feinstein unilaterally released the testimony of a key figure in the Russia probe.

It also looks like special counsel Robert Mueller may be gearing up to go after his biggest target yet.

Here's more on what you may have missed:

• Mueller sets his sights on 1600 Pennsylvania Avenue: Trump's personal defense lawyers are in talks with the special counsel about how to approach a possible interview request for the president. Business Insider also learned that Trump's legal team is leaning on a 1994 independent counsel investigation into a Clinton administration official as a roadmap to limit the scope of Mueller's questioning in the event of an interview.
• Trump refuses to commit to sitting down with Mueller: In an apparent departure from his remarks last year - during which he said he would be "100%" open to testifying under oath in the Russia investigation - Trump told reporters that he would "see what happens" if he's asked to submit to an interview. He added that because there was "no collusion," it would be "unlikely that you'd even have an interview."
• Trump's FISA flip-flop: The president sent lawmakers into a frenzy when he criticized the Foreign Intelligence Surveillance Act just hours after the White House released a statement voicing its strong support for it. In a tweet, Trump accused the previous administration of using FISA to spy on his campaign during the election. He later amended his position, reportedly after House Speaker Paul Ryan spent half an hour explaining the difference between domestic and foreign surveillance to him.
• The former spy who compiled the Steele dossier thought Trump was being blackmailed: Glenn Simpson, the co-founder of opposition research firm Fusion GPS, said in his testimony to the Senate Judiciary Committee that the former MI6 officer who put together the Trump-Russia dossier, Christopher Steele, went to the FBI last year because he was concerned that what he had learned about Trump's alleged Russia ties "represented a national security threat."
• Trump ramps up his attacks on the Russia investigation: After Sen. Feinstein released the Fusion GPS interview transcript, Trump lashed out at her and said in a tweet that "Russia & the world is laughing at the stupidity they are witnessing. Republicans should finally take control!" He also said during an interview with The Wall Street Journal that there was "no crime" and "no obstruction."
• FBI deputy director Andrew McCabe urged staff to "hang in there" after Comey's firing: McCabe, who became acting director after Comey's dismissal, added in a memo: "As men and women of the FBI, we are at our best when times are tough. Please stay focused on the mission, keep doing great work, be good to each other and we will get through this together."
  
• Russian hackers target the US senate: The hackers who breached the Democratic National Committee servers during the 2016 election are now laying the groundwork to infiltrate the Senate, a cybersecurity firm said. Researchers at the firm said that while the phishing emails sent out are not advanced, they could be "the starting point of further attacks that include stealing sensitive data from email inboxes."

Natasha Bertrand and Sonam Sheth contributed to this report.