US state department officials have issued a travel alert for Europe, warning people about "terrorist attacks". It's a grim sign of "normalisation", say experts, showing that Europe is now similar to other parts of the world.
Americans like to go to Europe in the summer - and US officials are now sending them off with a formal alert.
US travellers should watch out for potential "terrorist attacks" on people dining in restaurants, visiting shopping areas and riding buses, explain the officials in their memo, which was posted on the federal agency's website.
These kinds of travel alerts are routine, say people who've worked on counterterrorism issues at the state department. Besides that, it isn't even a dire notification.
"It's an alert - not a warning," says Dartmouth College's Daniel Benjamin, a former state department terrorism coordinator. "It's not at all unusual."
These kinds of alerts are issued on a regular basis, he says, as a way of telling US citizens to be careful when they visit other countries.
The notifications are composed and reviewed by intelligence officials who track potential threats from militant groups - but aren't concerned about a specific plot against Americans.
"It may have just been a response to signals and a lot of noise," says Henry Crumpton, who served as the state department's top counterterrorism official and is a former CIA officer.
Still that doesn't mean travellers should ignore the memo entirely.
As the US officials explain in their travel alert, the European football championship will be held from 10 June - 10 July. It'll attract large numbers of people - and in this way will provide "potential targets for terrorists".
In addition more than 2m people are expected at the Catholic Church's world youth day events in the Polish city of Krakow in July.
But whether people want to attend these events or just hang out in cafes in Berlin they should keep things in perspective. They shouldn't freak out - or worry too much about what might happen.
As Benjamin explains, people who visit European cities should be "mindful". But they can still have fun.
Richard Barrett, a former head of counterterrorism for MI6, says that US officials often issue these kinds of alerts when they hear about potential threats - just because they obliged to tell people about them. Not because anything is going to happen.
With this alert, the information that's provided is rather vague. As he says: "They're talking about the whole of Europe."
People who've worked in the state department says it's pretty easy to send out these kinds of alerts. They don't require extensive vetting And they get churned out on a regular basis for Pakistan and countries in other parts of the world.
"It's pretty standard practice for parts of the world where terrorism has become normalised," says Shamila Chaudhary, a former Obama administration official.
She says that some people may be surprised to hear about the alert in Europe. But they shouldn't be since, as she says, Europe is one of those places.
She says that the travel alert issued by state department officials serves as yet another reminder that the problem of "domestic terrorism" is now part of Europe. The travel alert shows that the danger is now being taken into account in a bureaucratic sense.
That means travellers from the US are now told about dangers that they could face when they go on their summer holiday - by officials in Washington.
"I think Europeans themselves - forget Americans - have been in denial about their domestic terrorism," she says, saying that the state department memo is forcing them to recognise how things have changed.
She says: "It's like - hey, Europe, welcome to the world."