Britain isn't worried about the proposed sale of a London-based port operator to a Dubai firm, but it will be up to Americans to decide about their own security concerns, British Deputy Prime Minister John Prescott said Wednesday. The proposed sale of the company with shipping operations at six major US ports has prompted opposition by American lawmakers on security grounds, though President George W. Bush has threatened to veto attempts to block the sale. "I think probably the president was right in that, wasn't he? He doesn't think it's a threat to security, but that's for the Americans to make their decision about it," Prescott said during a visit to Beijing. "We are certainly not worried about the change," he said.