IN THE aftermath of the G20 summit on July 7th and 8th, German politicians traded blows over who was at fault for riots by anti-globalisation activists that smashed up parts of central Hamburg. But a big global event in the heart of a city with a strong anarchist tradition was always bound to prompt protests. Officials’ deeper reasons for anxiety were different: Donald Trump and his attitudes towards Russia and Poland.

To some in Berlin, the president’s meeting with Vladimir Putin was a “Yalta 2.0”, a 21st-century equivalent of the summit in 1945 at which Americans and Russians divided Europe. Angela Merkel saw Mr Trump’s “back-slapping and face-pulling” display before the Russian president (as the Frankfurter Allgemeine Zeitung, a daily, put it) as undermining her efforts to confront Russia over Ukraine. An internal memo by the German foreign ministry summarising the G20 noted: “The summit went very well for Russia…As long as the US breaks rank, Russia can swim in the mainstream.”

All of this plays into Mrs Merkel’s fears that the multilateral order that has served her country so well is under threat. “Others were isolated—an experience that Putin visibly enjoyed,” reported the memo. It also observed disconcertedly that conservative Russian think-tankers like Andrey Kortunov and Fyodor Lukyanov viewed the summit as a “rebalancing” in global relations: from the old battle between developed and developing economies to a new one between globalists and nationalists.

Still, Berlin had largely priced in a rapprochement between Messrs Trump and Putin. A more unsettling development was Mr Trump’s visit to Warsaw before the G20, where the president’s speech echoed the ideologies both of Mr Putin and of Poland’s populist-nationalist Law and Justice government. The foreign-ministry memo described this as an “astonishing tectonic shift” in American foreign policy.

Most striking of all was Mr Trump’s venue: a summit of the Three Seas Initiative. Launched by Poland and Croatia, this new central European project recalls the “Intermarium” proposed by Jozef Pilsudski, the father of the country’s second republic, which lasted from 1918-39. Pilsudski dreamed of allying states on the Baltic, Black and Adriatic seas to oppose domination either by Russians or Germans. Warsaw presents its revival as a bid to improve north-south transport and energy links in the region, to complement better-developed east-west ones (see map). But Berlin suspects something more hostile. Consider the backdrop. Germany is already concerned about China’s “16+1” initiative with central and eastern European states, a series of investment projects that the Chinese expect will build influence in the region. The Germans are also putting pressure on the Polish government over its illiberal attacks on independent newspapers, judges and NGOs. And they are fending off Polish criticisms that their proposed “Nord Stream 2” gas pipeline from Russia to Germany will make Europe more dependent on Russia. So Mr Trump could hardly have done more to aggravate German officialdom. He endorsed the Three Seas Initiative. In meetings with the Polish and Croatian presidents he guaranteed a supply of American liquefied natural gas (LNG) and backed a corridor linking LNG pipelines in the two countries. Poland opened its first terminal on the Baltic sea at Swinoujscie in 2015, and the first American cargo arrived there last month. In Warsaw, Mr Trump encouraged the rapid completion of a Croatian LNG terminal at Krk, on the Adriatic. Though sensible, this looks to officials in Berlin like a bid to divide Europe and weaken Germany’s leverage over its neighbours. They are contemplating responses. One would be a new European infrastructure fund, to test whether Poland and its allies merely want more foreign investment or whether the Three Seas Initiative is actually about geopolitical balancing.

In years past, Germans developed a vision of a cohesive EU run from Brussels, steered mostly by Germany and underwritten by American power. Now they fear a future in which strongmen in Washington, Moscow and Beijing divide Europe and push around the pieces. Germany led the G20 meeting confidently, but it feels increasingly insecure.