US President Donald Trump says Nato countries have agreed to spend more on military budgets
Speaking after a two-day summit in Brussels, he said allies had committed to spending more than 2% of their annual output (GDP) on defence budgets.
The president has been highly critical of the alliance, complaining the US pays more than others.
After the meeting, he said he believed in Nato and it was "presently unnecessary" to consider quitting it.
Mr Trump has urged Nato allies to commit at least 4% of their annual output (GDP) to military spending.
Nato states are currently working towards a target of 2%.
President Trump used Thursday morning's meeting to demand that the 2% goal be met by 2019, according to reports.
Reuters news agency said he broke from "a carefully scripted session" about other Nato matters to emphatically restate his position.
Speaking shortly afterwards, German Chancellor Angela Merkel said there was a clear commitment to Nato from all attendees.
There has been concern that President Trump might quit the alliance.
Mr Trump's early-morning tweets from Brussels had been typically critical.
The US leader has specifically singled out Germany for criticism over its defence spending.
He has also accused the country of being held prisoner to imported Russian energy, saying it is "totally controlled" by Moscow.
EU figures suggest Russia is responsible for between 50% and 75% of Germany's gas imports but gas makes up less than 20% of Germany's energy mix for power production.