Mr Panetta said that while the remaining benefits are blocked by a federal law that does not recognise same-sex marriage, he foresaw a time "when the law will allow the department to grant full benefits to service members and their dependents, irrespective of sexual orientation".

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The reason is that how clogged an artery is does not predict that it will be the one to get totally blocked off and cause a heart attack.

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But the vehicle's unique capabilities mean it does not fit into any current regulatory regime, and unless that is changed its entry into service will be blocked.

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