A fundamental shift in interests and outlook is leaving the United States and Germany with potentially irreconcilable differences. This widening divide between Berlin and Washington may threaten the entire Western alliance.  

It should have been a marriage made in heaven. Barack Obama and Angela Merkel are quiet, pragmatic politicians less interested in grand gestures than in results, and both answer prayers from across the Atlantic. Merkel gives Washington someone to call when Europe is in crisis. Obama gives Europe the longed-for American leader willing to invest in multilateralism and multinational institutions.
 
So why does a widening divide between Berlin and Washington now threaten the entire Western alliance? A fundamental shift in interests and outlook in recent years leaves America and Germany with potentially irreconcilable differences.
 
US grand strategy relies not just on diplomats, soldiers and sailors but on trade negotiators as well, but even its economic initiatives are designed to serve geopolitical goals. Promotion of the Trans-Pacific Partnership, a promising multinational trade deal, is as much about establishing a counter to rising China as the shift of more US warships into Asian waters.
 
German officials, on the other hand, are focused ever more narrowly on economic stability and sustainability. Before the Eurozone descended into crisis, Germany appeared to be becoming a "normal" Western power, one interested in extending its political influence and willing to commit troops to defend its liberal values and security in Kosovo and Afghanistan. In recent years, however, Germany has become less instinctively multilateral and less willing to transfer sovereignty to supranational institutions such as the European Union or to take part in international missions. The result is a strange mix of economic assertiveness and military abstinence. Germany has become, in Hans Kundnani's memorable phrase, a geo-economic power, one that uses commerce to extend its influence and advance its interests.
 
We now have a clash between America's geopolitical ambitions and Germany's geo-economic agenda. Eighteen months ago, Germany surprised and infuriated the White House by joining Brazil, India, Russia and China in abstention on UN Security Council Resolution 1973, the proposal to create a no-fly zone over Libya. The German decision provoked speculation that Germany wanted to shed its supporting role in the US-led Western alliance in favor of the more independent, non-aligned and mercantilist-driven positions taken by leading emerging powers.
 
But the real rift began to open six months earlier during the G20 summit in South Korea. President Obama, who had spent weeks trying to rally developing countries behind the idea of global rebalancing, was taken by surprise when Chancellor Merkel made common cause with China and other export nations to oppose this stance. The German abstention on Libya made no difference to US plans, but at the G20, Berlin and Washington stood on opposite sides of the most fundamental questions now facing the world'sleaders: How can leading governments rebalance the world's trade relations, and should they stimulate demand or impose austerity? The answers to these questions will have crucial political consequences on both sides of the Atlantic.
 
Unfortunately, there is little Obama can do to win the Germans back.Washington can bolster the loyalty of other allies with offers of political access, military hardware, and vital intelligence. The commerce-minded Germans are not interested in these prizes. US officials gripe that Merkel will not listen to the president's economic advice for managing the Eurozone crisis. German officials counter that the world's second largest creditor has little to learn from its leading debtor.
 
Little wonder then that the latest couple turning heads is Berlin and Beijing, a match made in mercantilist heaven. On her recent trip to China, Chancellor Merkel notably did not allow fundamental differences in political values to complicate a budding "special relationship"
between the two countries.
 
In coming months, America and Germany will become further estranged.Differences over how to refloat the global economy will become more obvious and more important. US officials will lecture their European counterparts on the need for military burden-sharing. Europeans will insist that the demands of austerity will not allow them to spend more money on militaries while cutting everywhere else.
 
In the medium term, both US and German plans will fall short. Economic realities will limit America's geopolitical ambitions. It will take time for Washington to get what it wants from negotiations for the Trans-Pacific Partnership, and it's not clear how Washington will respond if Beijing uses its economic leverage to force its neighbors to choose between expanded security partnerships with America and deepening trade and investment ties with China.
 
Germany's focus on trade power will also encounter headwinds. Its lack of geopolitical influence will seem much more important if German demand for extended austerity in Europe feeds anti-German fury in Europe and if closer relations with Beijing force German officials to ignore ugly abuses of state power inside China. Angela Merkel's government could find itself short on influential foreign friends.
 
But the biggest challenge posed by this transatlantic estrangement extends well beyond US-German relations to the foundation of a liberal world order. Since the Cold War ended, America and Europe have advanced the principle that democracy, not single party rule, is key to political stability, and that market-driven capitalism, not state-directed development, is crucial for lasting prosperity. If America becomes less willing and able to advance these values abroad, and if Germany, Europe's engine, allies with fellow creditors over fellow democracies, who will be left to advance the principles that have politically and economically empowered hundreds of millions of people since the Wall came crashing down?

Ian Bremmer is the president of Eurasia Group and author of "Every Nation for Itself: Winners and Losers in a G-Zero World." Mark Leonard is the Director of the European Council on Foreign Relations.

A shortened version of this article appeared in the Washington Post.

Read more on: Europe and the world , European Power, German foreign policy leadership

The European Council on Foreign Relations does not take collective positions. This commentary, like all publications of the European Council on Foreign Relations, represents only the views of its authors.