The United States on Thursday described as 'positive' Iran's move to allow three detained US hikers to receive a visit from their mothers. 'It is a positive development. It is something that we have... pushed hard for,' State Department spokesman Philip Crowley told reporters when asked whether the move raised hopes for their eventual release. 'And we think, at this point, on humanitarian grounds.... there's something that Iran can do, and we would hope to see these three individuals released.' 