Donald Trump has taken a fresh swipe at key allies after a war of words broke out following the US president's decision not to endorse the conclusions of a G7 summit.
In a volley of tweets the US president, who is in Singapore to meet the North Korean leader, said: "Fair trade is now to be called fool trade if it is not reciprocal.
"According to a Canada release, they make almost 100 Billion Dollars in Trade with U.S (guess they were bragging and got caught!). Minimum is 17B. Tax Dairy from us at 270%."
Mr Trump went on to lambast fellow members of NATO for paying disproportionately less than the US to maintain the Western alliance.
"The U.S pays close to the entire cost of NATO – protecting many of these same countries that rip us off on trade (they pay only a fraction of the cost – and laugh!)," he tweeted.
"The European Union had a $151 billion surplus – should pay much more for military!"
The president renewed his attack on Canadian prime minister Justin Trudeau, who had hosted the G7 meeting in Canada, tweeting: "Justin acts hurt when called out!"
On Saturday, he called Mr Trudeau "very dishonest and weak".
And he launched a broadside at Angela Merkel's government, saying: "Germany pays 1% (slowly) of GDP towards NATO, while we pay 4% of a MUCH larger GDP.
"Does anybody believe that makes sense? We protect Europe (which is good) at great financial loss, and then get unfairly clobbered on Trade. Change is coming!"
On Sunday, Mrs Merkel labelled Mr Trump's use of Twitter to withdraw from the G7 communique on trade "sobering and a bit depressing".
The communique was supposed to illustrate shared ground between the US, Germany, the UK, Canada, France, Italy and Japan following Mr Trump's imposition of tariffs on steel and aluminium imports.
But unity was torn apart when the US president took exception to Mr Trudeau calling US policy "insulting".
Germany and France both issued robust responses to Mr Trump's decision to order US officials not to endorse the communique.
German foreign minister Heiko Maas posted on Twitter: "You can destroy an incredible amount of trust very quickly in a tweet.
"That makes it all the more important that Europe stands together and defends its interests even more offensively."
French president Emmanuel Macron's office issued a statement that warned "international co-operation cannot be dictated by fits of anger and throwaway remarks".
It added: "We spend two days working out a [joint] statement and commitments. We are sticking to them and whoever reneges on them is showing incoherence and inconsistency.
"Let's be serious and worthy of our people. We make commitments and keep them."
The response from Mr Macron suggests an end to what observers had noted was a budding "bromance" between the French president and Mr Trump.
Last year, the US president was wowed by a French military parade in Paris after being invited to join Mr Macron for his country's annual Bastille Day celebrations.
In return, Mr Trump made the French president his guest at his first White House state dinner, after which the US president said of his visitor: "I like him a lot."
At the summit, the world leaders had agreed a statement that read: "We acknowledge that free, fair and mutually beneficial trade and investment, while creating reciprocal benefits, are key engines for growth and job creation."
More from Angela Merkel
In response to Mr Trump's decision to withhold US support for the summit conclusions, a senior UK government source said: "We stand by the commitments made in the G7 communique."
Germany and France are also standing by the jointly agreed communique.