The leaders openly supported Ukraine's bid to become an official candidate to join the European Union. This is a significant step - Russia will almost certainly react angrily to any moves to admit Ukraine.EU leaders are preparing to make a decision next week on Ukraine's request to become a candidate. It is likely to be given the green light, although the process from candidacy to membership can take years.The Kyiv visit came as Russian troops were continuing their assault on the key city ofSeverodonetsk in eastern Ukraine.