As the commander in chief, Trump will have broad powers to declassify information and the highest level of access to the US government’s most closely guarded secrets but, at least for now, US allies are less concerned about revealing sources and methods to the new administration. Multiple officials described a robust process that scrubs identifying details from shared intelligence. But all mentioned concerns that the new president might take to Twitter to announce intelligence collected against adversaries in an emotional public outburst, similar to Trump’s constant targeting of perceived adversaries via social media during the campaign and transition period.

“Our leadership might be less willing to share important information that's sensitive for fear of seeing it on Twitter,” said an official with France’s Ministry of Defense, who like other security officials asked for anonymity because they weren’t permitted to publicly discuss intelligence-sharing arrangements. “Obviously stacking the [intelligence community] with political people loyal to him that share some of his more bizarre theories would hurt intelligence sharing.”

Adding to reservations many allies have harbored towards a politician with no diplomatic or security experience, Europe’s intelligence officers fear that Trump’s erratic statements and testy tweets could expose a successful intelligence operation or even inadvertently blow the cover on a foreign agent — worries that could lead them to cut back their intelligence sharing with the US.

Trump has spent weeks slamming US spy agencies for their conclusion that Russia secretly attempted to swing the election for him, going so far as to mock their work in favor of WikiLeaks’ Julian Assange, who asserted that a “14-year-old could have hacked” Hillary Clinton’s campaign chairman. Even in the hours before Trump was briefed Friday by the heads of US intelligence, he continued to call their reports of Russian subterfuge a “political witch hunt.”

“Cooperation comes from a sense of trust in the other side's motives and competence,” said a European military intelligence official, who asked his country not be named to avoid a political fight with the incoming administration. “If the leadership of the US behaves in an inept or unpredictable way, obviously that will hurt cooperation on issues like Russia,” the official said.

ISTANBUL — Intelligence services across Europe are growing increasingly worried that President-elect Donald Trump’s unpredictability and impulsive tweeting could harm intelligence-sharing agreements with the United States.

“Behaving erratically in public can leave a lot of room for misunderstanding on the strategic level.”

Foreign spies are already dissecting every one of the president-elect’s tweets, in hopes of gauging what US and Western spymasters know and how they know it.

“Tweeting by amateurs who want to impress with their knowledge lends to compromise of information,” said Malcolm Nance, a former US Navy cryptologist and the executive director of the Terror Asymmetrics Project on Strategy, Tactics and Radical Ideologies think tank in Hudson, New York. “The foreign agencies will be watching and reading into Trump’s words to find the sources of his information."



Not every US ally is worried. The US is so integrated with the UK’s intelligence agencies that it would take a “catastrophic” incident or clash to unravel the joint capabilities like codebreaking and eavesdropping developed over decades, said a former contractor at GCHQ, the UK’s signals intelligence agency.

That view is shared by several allies in the global fight against ISIS, who believe the collection and dissemination of intelligence will remain largely unchanged because of the close teamwork by members of the anti-ISIS coalition.

“In terms of the fight against ISIS and al-Qaeda, I doubt there will be much of a problem in terms of sharing tactical information,” said one intelligence officer with a European service who is based in the Middle East and focuses on ISIS.

“If we get something on a [high-value target] in Mosul, it’s all being filtered and analyzed through the same process that’s integrated with the Americans and a host of other countries,” the official said. “This is already happening at such a rapid pace, it usually doesn’t involve officials on the level of the president anyway. The larger concern is strategic intelligence: Will he be tweeting about things involving agreements or allies that might change the big picture? A perfect example is the situation currently involving the Russians, Turks, and the ISIS coalition. Behaving erratically in public can leave a lot of room for misunderstanding on the strategic level.”

Also, Egyptian officials appear unfazed by Trump, stressing that their 40-year intelligence relationship with the US could not be undone by a tweet.

“We need each other to continue this fight on terrorism,” an Egyptian official told BuzzFeed News.

Trump has said he wants to warm relations with the Kremlin and has praised Russian President Vladimir Putin, a former KGB officer, as “very smart.” That could lead allies to share less intelligence with the US about Russia or more drastically vet their distributed intelligence dossiers, which are already scrubbed of detailed information about how it was gleaned.

"It seems that if the administration's position is knee-jerk skepticism, that could potentially make US allies less likely to share Russia-related information with the US," said Daveed Gartenstein-Ross, a senior fellow at the Washington, DC-based Foundation for Defense of Democracies.

US officials recognize their European partners’ concerns that Trump’s brashness could diminish cooperation between agencies that depend on ambiguity and secrecy.

"We are in unchartered waters,” said one US official, referring to Trump’s personality, praise for Putin, and dismissal of US intelligence. “But yes, it could be a problem.”

Alberto Nardelli contributed to this article from London.