WASHINGTON — President Trump didn’t appear to break any law by sharing highly classified information with Russia, but that doesn’t make it any less problematic for America’s intelligence agencies and their overseas partners.

Even as Trump’s national security adviser insisted the disclosure to visiting Russian diplomats was “wholly appropriate” and routine, few people outside of the White House saw it that way. Especially troubling was that a foreign country provided the intelligence confidentially to the U.S.

A look at the legal and national security issues at stake:

What did trump tell the Russians?

Trump shared information about a threat from the Islamic State group while hosting Russia’s foreign minister and ambassador to Washington. The threat related to laptops carried on airplanes, according to a senior U.S. official.

The information appears to be related to the basis for a U.S. and British decision in March to bar laptops and tablets from being carried on board international flights from cities in Jordan, Egypt, Saudi Arabia and other Middle East countries. U.S. and European Union officials more recently have discussed expanding the ban to include flights from Europe.

Where did trump get the information?

A U.S. ally provided the information, the official said, meaning it wasn’t necessarily Trump’s to share with anyone else.

The New York Times reported that Israel was the provider, though administration officials wouldn’t confirm that was true.

The White House said Trump wasn’t briefed on the source of the intelligence and didn’t know where it came from when he passed it along to the Russians.

Was what trump did legal?

Probably.

The system for how U.S. secrets are classified and the rules for how they’re handled derive from an executive order.

That means secrets are governed by the president and not by laws passed by Congress. The president’s authority to make the classification rules comes from his constitutional powers as the commander in chief and head of the executive branch.

Typically, that has been interpreted to mean that the president has the ultimate authority to classify and to declassify information. Put another way, classified information becomes unclassified by default the moment the president chooses to disclose it.

But there are other laws that could come into play when sensitive information is disclosed to harm the U.S., according to David Pozen, who teaches national security law at Columbia Law School. These include the Espionage Act and Identities Protection Act.

Still, it’s hard to imagine the president being prosecuted under those laws given that it’s his constitutional power to make national security decisions.

So what’s the problem?

The disclosure to Russia appeared to violate an intelligence-sharing agreement that provides the U.S. with critical information about threats to the nation.

A breach of trust raises the possibility that U.S. friends might curtail such intelligence partnerships out of concern their secrets – and their sources and methods – could end up in the wrong hands.

The fact that the secrets went to Russia, an adversary of the U.S. and many of its allies, was especially alarming.

U.S. intelligence-sharing agreements include the Five Eyes program with Canada, Australia, Britain and New Zealand. These countries share vast amounts of information and promise not to spy on each other. The U.S. also shares intelligence with countries like Germany that broadly share U.S. national security goals.

Russia, a top espionage concern for the U.S., is different. Even sharing limited amounts of intelligence about terrorist targets with Russia, in Syria for example, has been the source of major controversy in the past.

And Russia’s allies and partners include Syria, Iran, China and other American rivals.

How have past presidents handled these issues?

Other American leaders routinely authorized disclosing certain secrets to other countries – but not the way Trump did it.

Typically, before disclosing intelligence to another country, there would be an evaluation of costs and benefits, close consultation with the U.S. intelligence community, and detailed consideration of how much to say and in what words so as to mitigate risks.

“That way, they can take steps to protect sources and methods,” said Steven Pike, a former State Department official who teaches at Syracuse University.

The White House acknowledged Trump made the decision essentially on the spot. In fact, it was so unexpected that officials later called the National Security Agency and the CIA to inform them of the breach of protocol and try to limit any damage.

What’s all this talk about “sources and methods?”

Intelligence agencies use the phrase “sources and methods” to describe secrets about how intelligence is gathered.

Even when intelligence is declassified, the government typically keeps secret the ways it acquired the intelligence. This way, it preserves its ability to collect more intelligence in the future. When the U.S. this week released details about prisoner killings in Syria, it didn’t outline exactly how it knew what it claimed to know.

Trump and his aides insist he did not reveal sources and methods to the Russians, and thus didn’t put intelligence-gathering at risk.

But intelligence experts say it’s not that simple.

Adversaries can often look at intelligence that has been disclosed and use reverse-engineering to find its source.

That raises concerns the Islamic State group might be able to identify a vulnerability that spies have been exploiting and cut it off.