WASHINGTON (AP) — When is an impromptu, after-dinner chat more than just "dessert"? When you're President Donald Trump, and your confection companion is Russian President Vladimir Putin.

Word of a second, lengthy conversation between the president and Putin earlier this month in Germany is adding yet another level of intrigue to Trump's entanglements with the Russian leader. Not only was the session undisclosed by both countries, but it took place with no aides present, save for a Russian government translator — a risky move, national security experts say.

The White House says it was merely a casual chat. Michael Anton, Trump's National Security Council spokesman said, "A conversation over dessert should not be characterized as a meeting."

To those concerned about potential Trump campaign collusion with Moscow in the election, it's yet another instance of a concealed Trump-Russia connection. To Trump's defenders, the uproar is the latest example of overblown outrage over something that would have be unremarkable in a pre-Trump world: two presidents chatting.

A look at what's at stake when the president decides to "wing it" with a foreign leader:

IMPROMPTU CHATS DO HAPPEN

In fact, sideline conversations are one of the most useful aspects of big international summits like the Group of 20 that Trump and Putin attended, veteran diplomats say, allowing leaders to interact without needing to schedule a formal meeting, which requires extensive planning and negotiations between the countries.

Trump's predecessor, President Barack Obama, frequently engaged with leaders spur-of-the-moment, including an historic handshake in 2013 with Cuban leader Raul Castro when they crossed paths at Nelson Mandela's funeral. At one economic summit in Beijing in 2014, Obama had three chats with Putin on a single day.

All those interactions either took place in view of cameras or were later disclosed by the White House. Jen Psaki, White House communications director under Obama, said the key error by Trump's team was to fail to disclose the meeting despite knowing the massive public interest it would elicit.

"The problem with the administration's explanation that 'this is normal' is that is Putin, and this is Russia. Not only has Russia been an adversary for some time, but this is a guy who directed an intervention into our election when Trump was elected," Psaki said. "Clearly, it's different."

Still, a spokesman for German Chancellor Angela Merkel, who hosted the summit, said Merkel wasn't "surprised or confused" by the Trump-Putin chat at dinner and said enabling a "lively exchange" among leaders was the whole point.

Added White House spokeswoman Sarah Huckabee Sanders, "It would be incredibly awkward to be at a dinner and not speak."

DESSERT OR NOT, A MEETING'S A MEETING

The White House sought to downplay the significance by noting the conversation took place over dessert at a dinner for leaders attending the summit. The White House described the meeting as brief. But Ian Bremmer, the columnist and consultant who revealed the meeting, said it lasted nearly an hour, to the astonishment of other leaders and spouses in the room.

Such a lengthy meeting is unlikely to have been limited to casual chit-chat. And Trump has a history of doing business during the final course: He's boasted of a productive conversation over chocolate cake in April with President Xi Jinping in which he informed the Chinese leader of his plans to launch airstrikes in Syria.

THERE'S POWER IN NUMBERS

Perhaps most striking is the fact that no Trump aides or American officials were present, such as a U.S. translator or note-taker. Putin did have his translator present, but typically the U.S. insists on having its own translator to ensure the president's words are conveyed correctly.

The White House attributed that to the fact that the chat was spontaneous and that each leader was allowed only one translator in the room. Putin's spoke English, while Trump had brought along his Japanese translator, since he anticipated talking with Japan's Prime Minister Shinzo Abe during the dinner.

But typically, if a Putin run-in was a possibility, the White House "advance" staff would have planned contingencies, including additional translators on standby in a holding room to be pulled in last-minute if needed, said a former senior U.S. official, who requested anonymity to discuss internal White House processes. In the Obama administration, the official said, aides ensured Obama was never alone with leaders of powerful, adversarial nations like China and Russia.

Generally, Obama's national security adviser joined him for chats with Putin. The absence of an official U.S. note-taker is especially troublesome, because it leaves Trump exposed to his words being mischaracterized, said Heather Conley, a Europe scholar at the Washington-based Center for Strategic and International Studies.

"The problem is you didn't have a third party there to say, 'No, this is what was said,'" Conley said. "It is critically important for there to be a record of what was assured, promised, discussed."

WHAT COULD GO WRONG?

It turns out, a lot. An unplanned conversation between U.S. Ambassador April Glaspie and former Iraqi dictator Saddam Hussein in 1990 triggered an explosive controversy over whether Glaspie had told Saddam the U.S. wouldn't intervene if he invaded Kuwait, which he did days later.

There was no U.S. note-taker to transcribe the conversation. So Glapsie was ill-positioned to challenge the veracity of an Iraqi transcript that suggested she'd given Saddam the green light.

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Reach Josh Lederman on Twitter at http://twitter.com/joshledermanAP