This week’s NATO summit was supposed to be a post-Brexit showcase for Britain but instead, the United Kingdom is mired in elections, the French and Turkish presidents are name calling and an impeachment-plagued U.S. President Donald Trump likely will be looking for a distraction.

The summit, which opens with a Buckingham Palace reception Tuesday evening, comes just days after a terror attack on London Bridge that left two people dead and three injured as the country prepares for Dec. 12 elections following Parliament’s failure to approve a deal to divorce the United Kingdom from the European Union. That divorce has been delayed until the end of January with no guarantee the new Parliament will be any more pliable.

The 70-year-old North Atlantic Treaty Organization was founded by the United States, Canada, Denmark, France, Iceland, Italy, Luxembourg, Netherlands, Norway, Portugal and the United Kingdom to counter the Soviet Union. Since then, it has expanded to include Albania, Belgium, Bulgaria, Croatia, the Czech Republic, Estonia, Greece, Hungary, Latvia, Lithuania, Montenegro, Poland, Romania, Slovakia, Slovenia, Spain and Turkey.

Trump has long complained the United States has carried too much of the financial burden of protecting Europe and reduced the U.S. financial obligation. The U.S. contribution has slipped from a high of nearly 6% of gross domestic product in 1989 to 3.42% this year. The European and Canadian contribution has fallen from nearly 3% of GDP in 1989 to just 1.55% in 2019. Trump said NATO countries should be contributing 2% of GDP for their defense.

In total dollars, the U.S. contribution (in 2015 dollars) has fallen from $741 million in 2012 to $685 million in 2019 for defense expenditures compared to $256 million in 2012 from Europe and Canada to $299 million this year, a 4.6% increase.

Former U.S. Vice President Joe Biden, who is seeking the 2020 Democratic presidential nomination, was critical of Trump's approach.

"There's always time for redemption, but up to now he's treated NATO like it's a protection racket. 'Pay more or we're not going to keep our commitment, in Article 5.' It's a sacred commitment. And I will say, I hope it goes well for the sake of the country," Biden said.

As the summit opens, Trump likely will be focused on developments in the impeachment investigation of his apparent effort to pressure Ukraine into investigating his political opponents and proving Ukraine, rather than Russia, interfered in the 2016 U.S. presidential election – a conspiracy theory U.S. intelligence officials have labeled a “fictional narrative” promoted by Moscow.

As he prepared to leave for London, Trump spent the morning Monday tweeting about the unfairness of the investigation by House Democrats while at the same time While House counsel Pat Cippollone advised the House Judiciary Committee neither Trump nor any of his representatives would participate in Thursday’s scheduled hearing on the impeachment process.

The House Intelligence Committee plans to release its findings following weeks of closed-door depositions and public testimony on whether Trump withheld $391 million in military aid to Ukraine as a means of pressuring Ukraine to do his bidding.

In the meantime, NATO Secretary-General Jens Stoltenberg tried to put a positive spin on the summit.

 “NATO is the only forum that brings Europe and North America together every day to address the key issues for our shared security,” Stoltenberg told a news conference Friday. “We are 29 allies, each with its own history, culture and political parties. So, we should not be surprised that sometimes we disagree.

“But the strength of NATO is that we have always been able to overcome our disagreements and unite around our core task: to protect and defend each other.”

Before heading for London, however, French President Emmanuel Macron and Turkish President Recep Tayyip Erdogan sniped at each other. After Macron called the NATO alliance “brain dead,” Erdogan, who has been testing out Russian weaponry, said Macron should test his own brain health.

“It will be a great tribute to how much all the NATO allies value the institution if we manage to get through this leaders meeting without President Trump, President Macron or President Erdogan doing something damaging to the alliance,” Kori Schake, a former National Security Council official in the George W. Bush administration and currently deputy director of the International Institute for Strategic Studies,” told Bloomberg.