MOSCOW (Reuters) – Russia will grant President Barack Obama permission next week to ship U.S. weapons supplies across its territory, or through its airspace, en route to Afghanistan, sources on both sides told Reuters on Saturday. The transit deal will open up an important corridor for the United States as it steps up its Afghan war against Taliban insurgents by sending in more troops. Routes via Pakistan have come under attack by militants. It will be one of the main agreements signed during Obama's Moscow summit next week with Kremlin chief Dmitry Medvedev, the sources said. "The agreement will include...