Dear Mr Butcher,

Request for Information under the Freedom of Information Act 2000

Further to our letter of 19 August 2009, in response to your Freedom of Information (FOI) request asking for details of the American use of hydrodynamics facilities at the Atomic Weapons Establishment at Aldermaston since 1992, I am now in a position to provide you with a substantive response. I am sorry for the delay and for not replying earlier.

As you will be aware from my colleague's letter of 25 June responding to your other request on this topic, the United States has participated, and continues to participate, in collaborative work with the UK at AWE Aldermaston to mutual benefit. These are under the auspices of the 1958 UK/US Mutual Defence Agreement (MDA).

In our previous letters we stated that exemptions s24 (National Security) and s27 (International Relations) of the FOI Act were believed to apply to the information that you have requested. On further investigation, however, we can confirm that all use of the hydrodynamics facilities has been collaborative, and it is therefore not possible to separate out any dates, costs or individual activities related to the either the UK or US programme. All activities at the facility have been and continue to be, for the mutual benefit of both the US and the UK. How each individual country chooses to use the data from the work at the hydrodynamics facility depends on their own plans and programmes.

If you are not satisfied with this response or you wish to complain about any aspect of the handling of your request, then you should contact me in the first instance. If informal resolution is not possible and you are still dissatisfied then you may apply for an independent internal review by contacting the Head of Corporate Information, 6th Floor, MOD Main Building, Whitehall, SW1A 2HB (e-mail [email address]). Please note that any request for an internal review must be made within 40 working days of the date on which the attempt to reach informal resolution has come to an end.

If you remain dissatisfied following an internal review, you may take your complaint to the Information Commissioner under the provisions of Section 50 of the Freedom of Information Act. Please note that the Information Commissioner will not investigate your case until the MOD internal review process has been completed. Further details of the role and powers of the Information Commissioner can be found on the Commissioner's website, http://www.ico.gov.uk.

Yours sincerely,