Catherine Ashton will be judged on how she responds to her first international emergency. Budget cuts might mean there will be less EU missions to crisis zones under her watch. So where will her first opportunity come from? Africa, the Middle East, or a crisis involving Russia?
Catherine Ashton needs a good crisis. While all eyes have been on the fight to save the euro, the EU's foreign policy chief has been focused on setting up the new External Action Service. Her supporters argue that she will be judged on how well this bureaucracy works - so she should not get distracted by bad news from, say, Thailand or the Koreas.
That is true up to a point. But Ashton is canny enough to know that real foreign policy influence comes from being able to take the lead in solving a crisis that others cannot stop.
Call this "Sarkozy's First Law of International Politics". The French president may be a bit volatile, but he won kudos for his personal diplomacy during the 2008 Georgian war.
Ashton's predecessor, Javier Solana, was a natural crisis manager. He started work for the EU fresh from guiding NATO through the Kosovo war. He went on to be the face of Western diplomacy with Iran, and was a frequent visitor to trouble-spots like Congo.
While Solana also oversaw the expansion of the EU's foreign policy machinery, he grasped that institution-building needed to deliver results to be credible. This led to a proliferation of EU peace operations - 22 since 2003. Not all these missions were strictly necessary or even strategically relevant, but they showed that the EU meant business.
There may be fewer such missions on Ashton's watch. For most of Solana's time in office, there were no major economic obstacles to deploying new operations. Now European diplomats are asking which of the EU's missions can be cut to make savings.
Some thoughtful officials in Brussels argue that, with the financial picture ever darker, it is time for the EU to invest less in ostentatious but expensive crisis management.
Instead, they argue, Baroness Ashton and the External Action Service should focus on longer-term strategic issues like revitalising international negotiations on climate change.
This may be right philosophically but tough politically. Ask UN Secretary General Ban Ki-moon. In 2007 he replaced Kofi Annan - who, like Solana, had built his reputation on crisis diplomacy. Ban opted for a deliberately different strategy, taking a low-key approach to conflict zones like Darfur while engaging world leaders on climate change.
The result: Ban has been praised for his commitment to the issue, but was marginalised at last December's Copenhagen summit. Meanwhile the UN has struggled badly in Darfur.
So Catherine Ashton needs to show she can tackle a crisis when it confronts her. Where might her first big crisis come from? Africa and the Middle East are both likely options.
There are signs of new trouble in Sudan and Congo, two countries the EU has tried to help stabilise. If either blows up, Ashton may find that European leaders - increasingly disinterested in African affairs - are all too willing to let her orchestrate their response.
The Middle East is another matter. Any crisis in the region is likely to centre on Iran, and Britain, France and Germany will all want a say in how to manage it - but may have very different solutions in mind. Ashton might find herself struggling to forge a consensus.
Harder still would be any crisis involving Russia, especially a new war in the Caucasus. Baroness Ashton would have to navigate between a bloc of member states from the eastern EU demanding a hard line on Moscow and some older members urging caution.
Leaders in both camps would want to take the reins - President Sarkozy, for example, might argue that he should repeat his 2008 diplomatic dealings with Dmitry Medvedev. Ashton would find it hard to claim she represented a truly common EU foreign policy.
But crisis management is inherently unpredictable: Ashton may find herself confronting threats from a completely unexpected quarter. While she builds up the External Action Service, she and her advisers should make sure that they are planning for the full range of shocks that may strike. Just one crisis - good or bad - could define her reputation.
This article is based on Richard Gowan's remarks to a Wilton Park conference on "The European Union's External Action Service: Ensuring Strategic Coherence and Effective Delivery", held on May 17-19 2010.
This article was first published by E!Sharp.
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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.