President Obama faces a knotty decision in whether to approve the much-delayed Keystone oil pipeline: a choice between alienating environmental advocates who overwhelmingly supported his candidacy or causing a deep and perhaps lasting rift with Canada. Canada, the United States' most important trading partner and a close ally on Iran and Afghanistan, is counting on the pipeline to propel more growth in its oil patch, a vital engine for its economy. Its leaders have made it clear that an American rejection would be viewed as an unneighborly act and could bring retaliation. Secretary of State John F. Kerry's first meeting...
