(CNN) Londoners did their best to keep calm and carry on after the latest night of carnage in a Western European city on Saturday.
But across the Atlantic, President Donald Trump used Twitter to stoke fear for political gain, lambasted London's Muslim mayor, then motorcaded to his nearby namesake luxury golf links.
On the one hand, Trump's response to the London attack, in which 7 people died only two weeks after a horrendous suicide bombing in Manchester, was par for the course.
After all, as a candidate Trump said himself that foreign terror attacks were good for his political fortunes -- and he's reacted to other foreign terrorist incidents by seeming to teeter on the edge of gloating that he had predicted them.
Still, his response to the London attacks was a jarring reminder of how his whiplash instincts shatter the mold of conventional presidential behavior.
It may also start a conversation about whether Trump is testing the limits of appropriate behavior for a head of state, let alone the leader of the West and whether his swift turn to politics as the dead were still being counted was in poor taste.
One thing is for sure, his Twitter spree after the London attack will have offended many people in Britain, where the President is already deeply unpopular. His brash attitude had already set European teeth on edge after his foreign trip last month.
To start with, as reports started to filter out of London, Trump retweeted a flashing siren Drudge Report alert.
"Fears of new terror attack after van 'mows down 20 people' on London Bridge..." the tweet read.
Considering that Trump has the most powerful intelligence machinery on the planet at his beck and call, it seemed odd that he would rely on the famed muckraker site to break the news.
At the time, there was no way to know whether the tweet was accurate or not and British authorities were warning about unsubstantiated reports.
London's Metropolitan Police had sent out their own tweet: "We are aware of reports on social media. We will release facts when we can -- our info must be accurate #LondonBridge."
As the horror unfolded in London, Trump, presumably watching on television, spotted a political opening, and touted his blocked plan to restrict entry into the United States of residents of a group of mostly Muslim nations.
"We need to be smart, vigilant and tough. We need the courts to give us back our rights. We need the Travel Ban as an extra level of safety!"
In fact, most recent terror attacks in the West have been carried out by homegrown or radicalized extremists, not foreign nationals -- meaning measures like the one he is proposing to bar travelers from six predominantly Muslim states are of questionable effectiveness.
And if it turns out that the assailants on Saturday were British they would have qualified for visa free travel into the US, invalidating Trump's point even further.
Trump did offer one less confrontational message of support.
"Whatever the United States can do to help out in London and the U. K., we will be there - WE ARE WITH YOU. GOD BLESS!" Trump tweeted Saturday night.
But those sentiments seemed likely to be lost in the rush of other tweets.
The accepted protocol in such situations would not be for a president to take to Twitter when no one knew what was going on.
In the past, US leaders have tended to wait for the facts before drawing conclusions, and to do everything to avoid politicizing the situation or angering a victimized ally at a time of national trauma.
Often a paper statement would follow -- likely after consultation across government departments and agencies.
An on-camera appearance expressing support and vowing to defeat terror wherever it emerges might follow.
That's never been Trump's way. And that's how his supporters like it, as they showed in the presidential election campaign by embracing his tough-on-terror rhetoric and critical commentary about Islam.
It's also true that the old ways do not seem to be stopping terror attacks occurring with increasing frequency across Europe.
Even so, the President's tweets show little evidence that he has considered how he might come across to those who do not support him. And they certainly don't seem to be laying out a plausible anti-terrorism strategy.
By playing the fear card, it could also be argued Trump is playing into the hands of the terrorists and he was certainly not doing any favors to British Prime Minister Theresa May, who has been criticized for her relationship with the President, and is facing a tougher-than-expected re-election race next week.
And, as so often before, there was a sense that the President responded to Saturday's attack though a prism of how it affected him, his beliefs and political goals, rather than through a wider geopolitical or humanitarian perspective.
A night's sleep didn't ease Trump's desire to turn the political screw.
"We must stop being politically correct and get down to the business of security for our people. If we don't get smart it will only get worse," he said on Sunday morning.
Next Trump chose to ignite a feud with Mayor Sadiq Khan -- an old adversary -- taking his words out of context to accuse him of being soft on terror.
"At least 7 dead and 48 wounded in terror attack and Mayor of London says there is 'no reason to be alarmed!'" Trump tweeted.
In fact, Khan merely told Londoners that if they saw extra police on the streets over the next few days "There's no reason to be alarmed."
His spokesman reacted with disdain to Trump's remarks -- in a display of disrespect a lowly political functionary would not normally dare to direct at a US President.
"(The Mayor) had more important things to do "than respond to Donald Trump's ill-informed tweet ," the spokesman said.
Washington's acting ambassador to London meanwhile appeared to contradict his boss.
"I commend the strong leadership of the @MayorofLondon as he leads the city forward after this heinous attack," read the tweet attributed to Lewis Lukens.
Opinion: After London, Trump should not let fear dictate policy
Trump still had some points to make, using the attack in which three men steered a van at pedestrians then went on a stabbing spree. The debate should be about terrorism, he appeared to argue, not the method.
"Do you notice we are not having a gun debate right now? That's because they used knives and a truck!" he tweeted.
Trump's critics in the US thought his tweets were off color.
"I don't think that a major terrorist attack like this is the time to be divisive and to criticize a mayor who's trying to organize his city's response to this attack," said former Vice President Al Gore on CNN's "State of the Union."
Washington Gov. Jay Inslee, a Democrat, rejected the idea that Trump was simply dispensing hard truths that people needed to hear.
"The people of London deserve from our American leadership courage and a commitment to a grand alliance. And what they have been given is just petty politics and insults," Inslee told CNN's Ana Cabrera.
There was no official UK government response to Trump's tweets. But the special relationship has been rocky since the President took office.
Earlier this year, the London government was furious when Trump suggested that British intelligence had helped the Obama administration hack into his phones. Then after the Manchester attack, May complained US spy agencies were leaking details given to them by intelligence sources in Britain.
When Trump later headed to his swank golf club along the banks of the Potomac, he either didn't remember, or didn't care that he had often lambasted former President Barack Obama for hitting the links at moments of global crisis.
"Can you believe that,with all of the problems and difficulties facing the U.S., President Obama spent the day playing golf. Worse than Carter," Trump wrote in one tweet in October 2014.
The President later returned to the London attack at an evening event at Ford's Theater, saying he had offered "unwavering support" to May in a phone call, before taking the chance to once again adopt his tough-on-terror posture.
"This bloodshed must end. This bloodshed will end," Trump said. "President I will do what is necessary is to prevent this threat from spreading to our shores."