A mysterious exchange between Trump and a foreign leader is Washington's latest obsession. Here's what is actually going on.

• A mysterious conversation between President Donald Trump and a foreign leader has captured Washington's attention and once again has the Trump administration at odds with House Democrats. 
• A member of the intelligence community in mid-August filed a whistleblower complaint that allegedly has to do with a promise Trump made to a foreign leader, among other matters.
• The acting director of national intelligence has refused to share the complaint with Congress.
• The matter has raised concerns about national security, respect for congressional oversight, and the integrity of the US electoral system. 
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A whistleblower complaint filed by a member of the intelligence community has sent shockwaves through Washington, as it allegedly accuses President Donald Trump of making an inappropriate promise to a foreign leader, among other acts.

The details surrounding the complaint are still hazy as the Trump administration is simultaneously denying the president did anything nefarious while working to ensure further information does not become public. 

Read more: 'DEFCON 1': US officials are rocked by a whistleblower complaint involving Trump's talks with a foreign leader

The acting director of national intelligence has refused to turn over the complaint, and his opacity has prompted yet another dramatic showdown between House Democrats and the Trump administration. 

The mysterious ordeal is also linked to broader tensions between Trump and the intelligence community, and his tendency to defy presidential norms in a manner that could jeopardize national security. 

Here's what we know:

• On August 12, a member of the intelligence community filed a complaint to the office of Intelligence Community Inspector General (IC IG) Michael Atkinson, who after a preliminary review determined it was credible and of "urgent concern."
• "Urgent concern" is defined as: "A serious or flagrant problem, abuse, violation of the law or Executive order, or deficiency relating to the funding, administration, or operation of an intelligence activity within the responsibility and authority of the Director of National Intelligence involving classified information, but does not include differences of opinions concerning public policy matters."
• Two weeks after receiving the complaint, Atkinson submitted it to the acting Director of National Intelligence (DNI), Joseph Maguire.
• Federal law requires the DNI to communicate or transmit complaints of "urgent concern" to Congress within seven days, but Maguire did not do this.
• In light of Maguire's refusal to contact Congress, Atkinson reported the complaint to the Senate and House Intelligence Committees in a letter on September 9, but did not offer specific details or the substance of the complaint. 
• California Rep. Adam Schiff, the chairman of the House Intelligence Committee, on September 10 requested a full, unredacted copy of the complaint, the IC IG's findings related to the matter, and all records connected to the Office of the Director of National Intelligence's (ODNI) involvement, "including any and all correspondence with other Executive Branch actors including the White House." 
• The ODNI officially declined the committee's request on September 13 and said Maguire is withholding the complaint in part because it "involves confidentially and potentially privileged communications by persons outside the Intelligence Community."
• Schiff on September 13 then subpoenaed the acting DNI to turn over the complaint. He said the acting DNI was required by law to turn over the complaint to congressional intelligence committees but refuses to do so.  
• Schiff also noted Maguire had consulted the Justice Department about the complaint, which is a major departure from the norm.
• Along these lines, Schiff raised concerns as to whether the ODNI "together with the Department of Justice and possibly the White House, are engaged in an unlawful effort to protect the President and conceal from the Committee information related to his possible 'serious or flagrant' misconduct, abuse of power, or violation of law."
• On September 15, Schiff told CBS News' "Face the Nation" that the acting DNI told the House Intelligence Committee that he was instructed not to turn over the whistleblower's complaint by a "higher authority."
• In a letter to Schiff on September 17, the ODNI's general counsel Jason Klitenic said the agency overruled the IC IG and determined the complaint didn't meet the definition of "urgent concern" under the law. 
• "This complaint, however, concerned conduct by someone outside the Intelligence Community and did not relate to any 'intelligence activity' under the DNI's supervision," Klitenic added. For that reason, after consulting with the Justice Department, the agency concluded it was not required to forward the complaint to the intelligence committees.
• Schiff had requested that Maguire appear before the committee on September 19 "absent compliance with the subpoena" in order to explain why he won't turn over the complaint, but Klitenic in his letter said the acting DNI "is not available on such short notice."
• On September 17, Atkinson wrote a letter to the intelligence committees that said he and Maguire were at "at an impasse," and added that the whistleblower complaint "not only falls within the DNI's jurisdiction but relates to one of the most significant and important of the DNI's responsibilities to the American people."
• The Washington Post on September 18 reported that Trump was the subject of the whistleblower complaint and that it related to communications between him and a foreign leader.
• The whistleblower lodged the complaint because the person was deeply troubled by a phone call Trump had with a foreign leader and, in particular, a "promise" Trump made during the call, according to the report.
• The Post reported that Trump interacted with at least five foreign leaders in the five weeks before the whistleblower filed the complaint: Russian President Vladimir Putin, North Korean leader Kim Jong Un, Pakistani Prime Minister Imran Khan, Dutch Prime Minister Mark Rutte, and Qatari Emir Sheikh Tamim bin Hamad Al Thani. 
• In a report on September 19, The Post said it had learned from two people familiar with the matter that the complaint "centers on Ukraine."
• Roughly two and a half weeks before the complaint was filed, Trump spoke with Ukrainian President Volodymyr Zelensky, who was elected in May. 
• House Democrats have been investigating whether Trump and his lawyer Rudy Giuliani have been attempting to persuade Ukraine to aid Trump's 2020 re-election bid by coercing "the Ukrainian government into pursuing two politically-motivated investigations under the guise of anti-corruption activity." As part of this, Democrats have requested the full transcript and a list of participants on a July 25 call between Trump and Zelensky.
• A report from The New York Times on September 19 also said the complaint is related to Trump and Ukraine but signaled it goes beyond any single phone call and involves multiple actions. 
• The IC IG in a closed-door briefing on September 19 told the House Intelligence Committee that the complaint was concerned with "multiple actions," CNN reported from sources familiar with the briefing. 
• CNN on September 19 also reported it had learned from three sources familiar with the matter that the White House has been involved in advising the acting DNI against sharing the whistleblower complaint. Schiff, however, has signaled he does not know if the White House is involved.
• "We do know that the Department of Justice has been involved in the decision to withhold that information from Congress," Schiff said on September 19. "We do not know - because we cannot get an answer to the question - about whether the White House is also involved in preventing this information from coming to Congress."

Here's what we don't know:

• We don't know who the whistleblower is or what department or agency they're from - the CIA, NSA, FBI, etc. -  and the IC IG is protecting their identity. 
• We don't know the precise details of the complaint or why it was of "urgent concern." 
• We don't know if the whistleblower directly witnessed Trump making inappropriate pledges to a foreign leader or learned about the details via other channels. 

What Trump is saying: 

• Trump has denied he said anything inappropriate and downplayed the significance of the allegations,  and has sent out multiple tweets to that effect. 

• Trump on September 20 claimed the whistleblower was "highly partisan," providing no evidence to support the assertion. 
• Trump later said he doesn't know who the whistleblower is, and defended his conversation with the unnamed foreign leader.
• "I don't know the identity of the whistleblower, I just hear its a partisan person meaning it comes out from another party," Trump said. "It was a totally appropriate conversation. It was actually a beautiful conversation."

What Democratic leaders are saying:

• In a statement on September 20, House Speaker Nancy Pelosi said: "Reports of a reliable whistleblower complaint regarding the President's communications with a foreign leader raise grave, urgent concerns for our national security. We must be sure that the President and his Administration are conducting our national security and foreign policy in the best interest of the American people, not the President's personal interest ... The President and Acting DNI's stonewalling must end immediately, and the whistleblower must be provided with every protection guaranteed by the law to defend the integrity of our government and ensure accountability and trust." 

Why this is such a big deal:

• It's out of the ordinary for a member of the intelligence community to lodge a formal whistleblower complaint about a sitting president. 
• The unprecedented nature of the situation prompted a former CIA official to tell Insider it's "equivalent to an imminent threat" in the intelligence community, adding: "DEFCON 1."
• "To be in this line of work and then to file a formal complaint against the sitting president and the commander in chief based on something he said - something that was so deeply alarming - that's an impossible situation to be in," one FBI agent who works in counterintelligence told Insider.
• Trump has been at odds with the intelligence community from the start (he's often referred to it as part of the "deep state") and his freewheeling approach to the presidency has been viewed by critics as a threat to national security. 
• This is yet another example of the Trump administration seeking to undermine Congress's oversight authority, which is an important part of the government's system of checks and balances. 
• If Trump and his allies have been working with a foreign government to influence the 2020 election, that's an extremely serious matter that would represent an assault on the electoral and democratic process in the US. 

What happens next?:

• Schiff has called Maguire to testify at an open hearing on September 26
• Schiff has also threatened to sue the Trump administration to gain access to the complaint if necessary. 

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