Europe must help the rest of the world by getting its financial house in order quickly, U.S. President Barack Obama said in an opinion piece Friday. The article appeared in the Financial Times in advance of next week\'s Group of 20 summit in France. Obama said European leaders had agreed on a helpful strategy this week. \"Given the scope of the challenge and the threat to the global economy, it is important for all of us that this strategy be implemented successfully -- including building a credible firewall that prevents the crisis from spreading, strengthening European banks, charting a sustainable path for Greece and tackling the structural issues at the heart of the current crisis,\" he wrote. While the G20 helped start a recovery two years ago, the world economy is still \"fragile,\" Obama said with high unemployment in many countries. He promised as president of the country with the world\'s biggest economy to foster recovery in the United States. A third necessity is \"balanced and sustainable\" growth, the president said. He said that the countries in the G20 must also commit to moving away from fossil fuels and must help poorer countries develop their economies.