Brussels: European Council President Donald Tusk told US President Donald Trump on Tuesday to stop berating NATO allies over military investment levels ahead of what is expected to be a fraught alliance summit.
Before taking off for Brussels, Trump again chided fellow NATO members for not contributing enough to the alliance while maintaining a trade surplus with the United States, his latest reprimand on issues that are straining transatlantic relations.
"Dear America, appreciate your allies, after all you don't have that many," Tusk, a former Polish prime minister, said after a signing statement on more cooperation between the European Union and the North Atlantic Treaty Organisation.
As European Council president, Tusk serves as the chairman when EU leaders meet at summits.
NATO released new estimates for allied defence spending in 2018 on Tuesday, showing that Latvia and Lithuania are set to meet the target of spending 2 per cent of economic output on the military.
Of the 29 allies, only the United States, Britain, Estonia, Greece and Poland met the goal in 2017.
Romania is also on course to hit it in 2018, NATO said.
Many US presidents have urged European governments to spend more on their militaries.
But Trump has intensified the demands to such an extent that allies worry it could damage NATO morale and play into the hands of Russian President Vladimir Putin, who they accuse of trying to destabilise the West.
"Dear President Trump: America does not have, and will not have a better ally than Europe," said Tusk.
"Today, Europeans (collectively) spend on defence many times more than Russia, and as much as China."
He said that money helped boost US security, as the United States regards Russia and China as threats.
NATO Secretary-General Jens Stoltenberg stressed that all allies were increasing defence spending in real terms because economies in Europe were growing.
He also said Washington strengthens its security and global reach through NATO.
"NATO is the force multiplier for the United States," Stoltenberg told reporters.
Trump's tweet on Tuesday echoed earlier posts on Twitter on Monday and his criticism at a rally of supporters in the United States last week, in which he said that Washington was unfairly carrying almost all the cost of defending Europe.
"Getting ready to leave for Europe. First meeting - NATO. The US is spending many times more than any other country in order to protect them. Not fair to the US taxpayer," Trump said.
As he left the White House, the Republican president was asked about Tusk's comments.
"We do have a lot of allies, but we cannot be taken advantage of. We're being taken advantage of by the European Union," he told reporters. European officials say while US defence spending makes up 70 per cent of combined allied governments' military budgets, just 15 per cent of US expenditure is spent in Europe on NATO-related defence.
Washington pays about 22 pe rcent of the running cost of NATO, including the headquarters and commonly-funded equipment such as AWACS surveillance planes.
"On top of that we lose $151 Billion on Trade with the European Union. Charge us big Tariffs (& Barriers)!" Trump also said in the same tweet.
EU and US government data put the US trade deficit with the EU at around $100 billion, including services such as finance, where the United States has a surplus.
EU officials also say most tariffs on US goods are already low to zero.