Reports are circulating which indicate Britain rejected U.S. requests to use British bases as part of a larger buildup in the Gulf.
Britain was concerned that if such a buildup were part of an "pre-emptive strike on Iran," it would "violate international law."
Anonymous British officials have indicated the U.S. requested access to bases "in Cypress and British territories in the Atlantic and Indian oceans as part of a contingency plan for Iran," but Britain said no.
According to a British defense official, "The UK would be in breach of international law if it facilitated what amounted to a pre-emptive strike on Iran. It is explicit. The government has been using this to push back against the U.S."
For the record, the Obama administration claims it has made no formal requests to Britain for base access. Moreover, the admin maintains that the route they're taking toward Iran continues to be a diplomatic one.