Mrs Merkel's status as Europe's go-to leader will be on display when US President Barack Obama hosts her at the White House on Monday. Two days later, she is set to be in Minsk, Belarus, for four-way talks with French President Francois Hollande, Russian President Vladimir Putin and Ukrainian President Petro Poroshenko. The biggest risk for Mrs Merkel is if either crisis spiralled out of control. At that point, she would have failed to address "German concern about stability," Dr Hamilton said. The leaders of Russia, Ukraine, Germany and France agreed to meet in Belarus on Wednesday to try to broker a peace deal for Ukraine amid escalating violence there and signs of cracks in the trans-Atlantic consensus on confronting Vladimir Putin. The four leaders held a call on Sunday, two days after Mrs Merkel and Mr Hollande travelled to Moscow for talks with Mr Putin that produced no breakthrough in the nearly year-long conflict that has claimed more than 5000 lives. After the call, Mr Poroshenko said progress had been made and he was hopeful the meeting in Minsk would lead to a "swift and unconditional ceasefire" in eastern Ukraine, where pro-Russian separatists have stepped up a military offensive in recent weeks, seizing new territory.

A Ukraine military spokesman said on Sunday that intense fighting was continuing around the rail-junction town of Debaltseve, with rebel fighters making repeated attempts to storm lines defended by government troops. Mrs Merkel came under sharp criticism from US senators Lindsey Graham and John McCain, both Republican hawks, for opposing the sending of defensive weapons to the Ukraine army to help it fight the separatists. "The Ukrainians are being slaughtered and we're sending them blankets and meals," Mr McCain said in Munich. "Blankets don't do well against Russian tanks." While Mrs Merkel, 60, does not deliver grand visions of European unity and reconciliation as her mentor Helmut Kohl did, she has a practical set of values that are now under threat. For the 19-nation currency bloc, her goal is to make economies from Greece to Ireland more like her export-driven powerhouse. She says changes are vital to adapt to globalisation and Europe's ageing populations as deflation threatens the eurozone and growth is stuck about 1 per cent. At the same time, bailouts she backed have spawned a challenge by the anti-euro Alternative for Germany party that limits her leeway for cutting another deal with Greece.

In Ukraine, Mrs Merkel sees Mr Putin's annexation of Crimea and the advance of Russian-backed separatists as a breach of the post-Cold War order that thrust a peace-seeking Germany to the centre of the continent's map. A physicist by training, Mrs Merkel uses trial and error to make policy and tries to wait out opponents she cannot immediately defeat. She has been honing that tactic, denying Mr Putin a face-to-face meeting for more than two months until Friday and stalling Greek Prime Minister Alexis Tsipras on his demands for easier bailout terms. "We're waiting for proposals, then we'll enter into talks," she said February 3 when asked about Greece. As fighting escalated in Ukraine, another Mrs Merkel came into view - the pragmatist who is ready to change tack. After telling Mr Putin for weeks she would not meet him unless he produced tangible peace overtures, she joined Mr Hollande for talks in Moscow. She will meet Mr Tsipras for the first time at a February 12 European Union summit. "How she'll handle these days will define her historic legacy," said Irwin Collier, an economist at Free University in Berlin who has followed German politics for two decades. "The immediacy and urgency of taming the dual Greek and Ukraine nightmares are defining moments for Europe and Merkel."

Ukraine's conflict has turned into a game of chicken between Mr Putin, the former Soviet KGB spy who learnt Mrs Merkel's language in her East German homeland, and Mrs Merkel, the math whiz whose high-school Russian was so good she won a trip to Moscow. Mr Putin's German is better than Mrs Merkel's Russian, so banter between them tends to be in German, according to a person familiar with their conversations. When Mr Putin is pressed about his policies, he switches to formal Russian, the person said. That connection has not prevented their estrangement. Mrs Merkel still sees the KGB agent's mindset in Mr Putin, according to the two German officials. The Kremlin views Mrs Merkel as abandoning a balanced approach and taking a pro-US line against the Kremlin on Ukraine, according to a Russian official. All three asked not to be named. For all their shared past, Mrs Merkel takes an unemotional view of the German-Russian partnership, mirroring her view of Europe. "She and Putin both grew up in the east bloc, so they're on similar wavelengths," Karl-Heinz Kamp, head of the German government's Academy for Security Policy in Berlin, said. "No other country or leader has Merkel's clout to be the go-between for Russia and Europe."

Last northern autumn, mounting deaths in eastern Ukraine and Russia's denial of involvement cemented the gap between them. It widened at the Group of 20 summit in Brisbane in November after the two met for almost four hours. "Step by step" emerged as Mrs Merkel's mantra during the debt crisis, when she refused to heed demands by the US and European allies to deploy more German resources to halt the turmoil. Germans like it, regularly ranking her as the most popular politician in polls. Mrs Merkel is also hemmed in by Germany's militaristic past and the legacy of the Holocaust. "The alternative is a German leader that speaks out forcefully on every issue and that would invite - that is the German view - countervailing coalitions against the Germans," Dr Hamilton said. "You can see that on the euro issue. She's criticised as not being forceful enough, but in Greece people compare her to Hitler." Bloomberg, Reuters