Leaders from across the North Atlantic Treaty Organisation arrived in London to celebrate the seventieth anniversary of the alliance. Yet the gathering was noted for its tensions rather than its harmony.

While Boris Johnson (the British Prime Minister and the summit’s host), reaffirmed his country’s “rock solid” commitment to NATO and reiterated the idea of “one for all, and all for one,” this was certainly not the attitude between U.S. President Donald Trump and his French counterpart Emmanuel Macron. On the first day, the two figures clashed over a number of issues.

This was not unexpected given Macron’s comment last month about NATO being “braindead,” due to the perceived declining American commitment towards the alliance. In typical fashion, Trump lashed out by accusing Macron of being “very disrespectful” as well as attacking France for having “a very high unemployment rate.”

Disagreements continued over the issue of military spending as well as the question of what to do with foreign ISIS fighters. The two did agree, however, in their opposition to Turkey’s decision to buy Russian-made S-400 missiles: Trump suggested the possibility of sanctions, while Macron asked “how is it possible to be a member of the alliance… and buy things from Russia?”

Central to a lot of the disagreements was Turkey. In addition to Russian arms purchases, the country made headlines over its continued involvement in northern Syria, which it sees as part of the battle against terrorism. Turkish President Recep Tayip Erdogan made it clear that he would oppose a NATO defence plan for the Baltic states and Poland if the member states continue to remain reluctant in recognising the YPG as a terrorist organisation.

Turkey currently has the second largest army in NATO, after the U.S..

Like other disputes involving the United States, the ones with NATO member states are at times intertwined with financial and economic issues. Trump has repeatedly raised the matter of defence spending, since the majority of the NATO countries are not spending the agreed 2 percent of their GDP on defense. Jen Stoltenberg, NATO’s Secretary-General, did highlight however the fact that Canada and the European states have added $130bn to their defence budgets since 2016 — a figure set to increase to $400bn by 2024. Additionally, the U.S. is currently in a trade dispute with the EU and has increased tariffs on Canada as well as weakened the Turkish economy.

Growing uncertainty about the transatlantic relationship has resulted in France and Germany increasingly advocating for a stronger European defence — though one that would not necessarily replace NATO. In the meantime, ahead of its general elections on December 12, Britain still struggles with the Brexit imbroglio and is unsure about its future relationship with its continental neighbors, including on security matters.