Some of Mr. Romney’s most provocative language — calling Russia the nation’s pre-eminent foe, promising a virtual trade war with China and rattling sabers for a possible strike on Iran — seems calculated at least in part to appeal to conservatives eager for a more muscular policy. Mr. Romney will surely feel compelled by his own campaign language to enact tougher policies than Mr. Obama in those areas once in office, and conservatives have made clear they will hold him to his words.