President Donald Trump departs for London on Monday to attend a NATO leaders meeting that is designed to showcase the continued strength of the alliance 70 years after its establishment. But the gathering will also put the political strains within the alliance on public display.

rump, who once famously declared NATO to be “obsolete” only to later say is was “no longer obsolete,” has disrupted the status quo within the organization over the last three years. His most persistent complaint is that the U.S. is footing more than its fair share of the bill, while calling on other members to increase their spending.

But he is not the only leader attending this week’s summit to have upset the status quo.

French President Emanuel Macron recently sent shockwaves through the alliance by making a provocative warning of NATO’s “brain death,” while Turkey’s President Recep Erdogan acted out of accord by invading Northern Syria and with his purchase of Russian military equipment.

Trump, for his part, has made strides toward his goal of reducing the U.S. financial commitment to NATO.

“The president has been spectacularly successful,” a senior administration official said in a call with reporters. “In 2016, only four allies spent 2% of GDP on defense. Now, there are nine, and following through their implementation plans to get the 2%, we expect there to be 18 by 2024. This is tremendous progress, and I think it is due to the president’s diplomatic work.” Read more

Read also: Now even the FBI is warning about your smart TV’s security

President Donald Trump departs for London on Monday to attend a NATO leaders meeting that is designed to showcase the continued strength of the alliance 70 years after its establishment. But the gathering will also put the political strains within the alliance on public display.

President Donald Trump departs for London on Monday to attend a NATO leaders meeting that is designed to showcase the continued strength of the alliance 70 years after its establishment. But the gathering will also put the political strains within the alliance on public display.