The international system of alliances created after the Second World War is breaking apart. This reality is on display at the G7 summit, which concludes Saturday in Taormina, Sicily.

European Council President Donald Tusk said on the eve of the meeting, “There can be no doubt that this will be the toughest G7 summit in many years.”

The European media have identified the cause for the crisis as the provocative and erratic behaviour of US President Donald Trump. But Trump is merely the expression of much more fundamental tendencies. Almost a decade after the global financial crisis, which brought the world economy to the brink of collapse in 2008, the conflicting interests among the imperialist powers have reached a point at which they can no longer be reconciled through talks and diplomacy. This was made clear above all in the areas of trade and climate change policy, two of the most contentious issues at the summit.

On Thursday, Trump strongly criticised Germany’s economic policy. At a meeting with European Commission President Jean-Claude Juncker and Tusk in Brussels, he described the Germans as “bad, very bad,” and threatened to stop the sale of German cars in the US.

At the subsequent NATO meeting, Trump denounced the assembled heads of government. “Twenty-three of 28 member states are not paying what they should be paying,” he accused. This was unfair towards “the people and taxpayers of the United States.”

On the flight to Italy, Trump’s economic adviser Gary Cohn repeated his threats. “We will have a very controversial debate about trade and we will talk about what free and open means,” he said. The issue was making the rules of the game fair, he added. The US would “treat other countries like they treat us.”

Cohn described the Paris Agreement on climate change as “unjust” because it restricted economic growth in the United States and created “unequal conditions for competition.” There would be “quite a robust discussion” at the summit about the matter.

Trump promised during the election campaign that the US would withdraw from the climate change agreement, which was finalised at the end of 2015 and has since been signed by the US, China, the European powers and several other countries. The other G7 countries—Germany, France, Britain, Italy, Japan and Canada—are warning against the US leaving.

A confrontation developed Friday during the first order of business at the summit. The US delegation blocked a proposal for dealing with the refugee crisis presented by the Italian hosts.

The Italian government, which plays a key role in sealing off the Mediterranean Sea to migrants fleeing wars in the Middle East and Africa, intended to recognise, at least verbally, the rights of refugees. But the US categorically rejected this. According to informed sources, US negotiators were not prepared to negotiate and stood by the position, “Take it or we’re doing nothing.”

In the draft declaration, at the insistence of the United States, there is only one sentence on refugee policy that sets out, “We confirm the right of states to control their borders and set clear limits for migration.”

The European media and politicians raged about the “mistaken, brutal and boorish methods of Donald Trump” (the French daily Le Monde ). The outrage reached fever pitch in Germany.

It may be the case that the European powers behave more politely and with more political correctness than the American president, but they pursue their global economic and geostrategic interests just as unscrupulously as he does.

In a lead article on Trump’s visit to Brussels, the German daily Süddeutsche Zeitung noted that the EU is seeking to counteract the nationalist “America first” policy by posing as advocates of open markets. It added, “The Europeans are determined to fill the hole that the US will leave after Trump’s rejection of world trade. The European Commission is currently negotiating, on behalf of the EU states, some 20 trade deals around the world, including with countries like Japan, Singapore and Vietnam.”

Under the pressure of declining economic growth, unstable financial markets and sharpening social tensions, a bitter struggle is once again erupting between the imperialist powers over markets, raw materials and strategic influence. As during the first half of the 20th century, each capitalist nation-state is attempting to obtain the upper hand against and push back its opponents.

The predecessor of the G7, the Group of Six (Canada had not yet joined), was established in 1975 in response to the first major economic crisis in the post-war era. The leaders of the six most powerful economies met at Rambouillet Palace for “fireplace discussions” to prevent the breakdown of the Bretton Woods system and the first major oil crisis from leading to trade war and military conflict.

In 1998, the G7 was expanded to include Russia and became the G8. Russia was expelled in 2014 for its annexation of Crimea. The conflicts and tensions between the remaining members are now growing. These developments not only call into question the continued existence of the G7, but also NATO, the most important military alliance of the past 70 years.

Observers took notice of Trump’s refusal during his Brussels visit to reaffirm his commitment to Article 5 of NATO, which commits all member states to come to the assistance of a NATO member in case of attack.

The Financial Times commented, “Mr Trump’s failure to endorse the alliance’s mutual defence clause came as a shock. Nicholas Burns, who was US ambassador to Nato on 9/11, described it as a ‘major mistake’, noting on Twitter that ‘every US president since Truman’ has pledged support for Article 5. ‘Not so Trump today at Nato’.”

NATO was always a reactionary military alliance, which either as a whole or as part of shifting coalitions has played a major role in the neo-colonial wars in the Middle East and North Africa, and in the military build-up against Russia. But if it should now break apart under the pressure of its internal conflicts, this would result in wars between the Western powers being once again possible and even probable.

As in 1914 and 1939, the crisis of the capitalist global order is leading once again to war. The only way to prevent such a catastrophe is through the building of an international anti-war movement, which is rooted in the working class and fights for a socialist programme.