Trump reportedly shared secrets with the Russians. Will it put lives at risk? Is it impeachable?

In a fit of boastful over-sharing, Donald Trump last week allegedly disclosed highly secret "code-word information" with Russian diplomats in the Oval Office, an astonishing intelligence leak to a foreign rival that threatens to:

• Revive demands for the president's impeachment.
• Jeopardize the U.S.'s international espionage relationships.
• Endanger a key spy or multiple intelligence sources with access to the inner workings of ISIS.
• Intensify the investigation of the Trump campaign's alleged ties with the Kremlin during the 2016 election.

Experts on presidential powers say Trump can officially talk about almost any classified information he wants, even leaking it to adversaries like the Russians, as he allegedly did last week during a meeting in Washington with Russian Ambassador Sergey Kislyak and Foreign Minister Sergey Lavrov, at least five major media outlets have reported.

"The president didn't break the law, but there's a difference between breaking the law and doing things that put the country's national security or other nations' intelligence individuals in danger," says John Hudak, deputy director of the Center for Effective Public Management at the Brookings Institution. "There's the letter of the law and there's the responsibility the president should have."

• Trump revealed classified info to Russians in Oval Office: U.S. officials

In a careful statement on Monday, National Security Advisor H.R. McMaster denied that "intelligence sources and methods" were ever discussed, but neither of those two details were mentioned in the original Washington Post story. Critics shredded McMaster's remarks as a deftly worded non-denial denial, noting he never explicitly denied classified information was shared.

• Democrats want any Russia investigation kept clear of Trump's 'heavy hand'
• Comey was pushing Trump-Russia probe harder in days before firing, officials say​

Treason allegations would not stick, but Hudak notes the impeachable offence of "high crimes and misdemeanours" is much more open to interpretation.

"Most people would agree that if the president, in offering this information, ends up getting people killed, that would probably rise to the level of a high crime," Hudak says. "But the reality is a president can be impeached for whatever Congress wants to impeach him for," given there is enough political will to do so.

At this point, that does not appear to be the case. Impeachment proceedings to undo an election outcome are inherently undemocratic and would likely require overwhelming voter support.

Intel on ISIS

The "code-word" designation denotes the highest level of classification. In this case, as reported first by the Washington Post and confirmed by the New York Times, citing current and past U.S. officials, the information concerned information from a U.S. partner about ISIS using laptops to bring bombs onto airplanes.

Mark Lowenthal, a former assistant director with the Central Intelligence Agency, was appalled by the reports of Trump's sensitive disclosures. Among his worries is the potential damage done to the dozens of intel-sharing "liaison relationships" the U.S. retains.

"The president likes to brag.… And whoever provided us with this intelligence, they're really pissed," Lowenthal said. "Other countries that provided us with intelligence are saying, 'Aw crap, can we share stuff with the Americans? Are they going to go blow all this stuff up?'"

Meanwhile, the president's actions may well have imperilled agents in the field, Lowenthal says.

"These are people out there collecting intelligence in dangerous circumstances. Their government is sharing with us and now suddenly they are in serious trouble because, I'm sorry, but you can't trust the Russians."

'Serious jeopardy'

A concern for the intelligence partner whose material was shared by Trump with Russia without that partner's permission will be the safety of its source. An immediate effect of the leak, for example, may be that an operative must now go into hiding.

"Depending on how much would be necessary to deduce that source, it's certainly possible there would be a person or persons in some serious jeopardy right now," says national security analyst Elizabeth Goitein with the Brennan Center for Justice.

The Post reported that senior White House officials alarmed by Trump's disclosures scrambled to contain the leak, alerting the CIA and the National Security Agency.

In a "fragile" intel-sharing network, there may also be a deep freeze on the U.S.'s espionage relationships with some allies, Goitein said. She expects tension among the global intel community "around the margins," though perhaps not an "all-out intelligence blackout" between more reliable partners such as the United Kingdom.

More 'Russia problems'

Trump's persistent failure to detach himself from "an accumulation of Russia problems" is particularly remarkable to Rajan Menon, an international relations professor at City College of New York, who studies Russian foreign policy. At a time when the White House press office has tried to suppress the significance of the Trump-Russia investigation, the president himself continues to dump more fuel on the fire.

Democrats and even some Republican lawmakers may feel emboldened to push for a tough inquiry and perhaps press for an independent special prosecutor.

"Think of Russia as an exploding cigar. It's supposed to explode once, but in the case of Trump it explodes in his face again and again," Menon said. "This just keeps the Trump-Russia controversy alive."

U.S. foreign policy toward Russia suffers as a result, he said, as any diplomatic moves the president hopes to make regarding the Kremlin will immediately raise suspicions that Trump is subject to "kompromat" — the Russian term for compromising material or blackmail.

"Whether it's arms control or terrorism or Syria or North Korea, Russia is an important country, and whatever you think of [Russian President Vladimir] Putin, you cannot not deal with Moscow," Menon said.

If the reports from multiple credible media outlets prove to be true, Menon foresees at least two grave problems in the administration.

"You have senior officials denying it happened; and the president at the very least exercising spectacularly bad judgment," he said. "I don't know if this is the last straw, but you can't deny we're deep in a very, very serious problem either way."