LONDON (Reuters) - Britain will not speculate on what will happen if the United States withdraws from an international deal to curb Iran s nuclear program, Prime Minister Theresa May s spokesman said on Thursday. He said Britain s government has been crystal clear about the importance of the deal and its ongoing commitment to it.  As for speculating on what happens next, I m not going to do that,  the spokesman said when asked about a possible U.S. decision to decertify the deal. 