United States–European Union pact on one side and Iran on the other over Iran's nuclear program also continues to develop, remaining a serious obstacle in the improvement of Tehran–London ties. A confidential letter by UK diplomat John Sawers to French, German and US diplomats, dated 16 March 2006, twice referred to the intention to have the United Nations Security Council refer to Chapter VII of the United Nations Charter in order to put pressure on Iran. Chapter VII describes the Security Council's power to authorize economic, diplomatic, and military sanctions, as well as the use of military force, to resolve disputes. The Sunday Telegraph reported that a secret, high-level meeting would take place on 3 April 2006 between the UK government and military chiefs regarding plans to attack Iran. The Telegraph cited "a senior Foreign Office source" saying that "The belief in some areas of Whitehall is that an attack is now all but inevitable. There will be no invasion of Iran but the nuclear sites will be destroyed." The BBC reported a denial that the meeting would take place, but no denial of the alleged themes of the meeting, by the UK Ministry of Defence, and that "there is well sourced and persistent speculation that American covert activities aimed at Iran are already underway". 2004 Iranian seizure of Royal Navy personnel On 21 June 2004, eight sailors and Royal Marines were seized by forces of the Revolutionary Guards' Navy while training Iraqi river patrol personnel in the Persian Gulf. 2007 Iranian seizure of Royal Navy personnel On 23 March 2007 fifteen Royal Navy personnel were seized by the naval forces of the Iranian Revolutionary Guard for allegedly having strayed into Iranian waters. Eight sailors and seven Royal Marines on two boats from HMS Cornwall were detained at 10:30 local time by six Guard boats of the IRGC Navy. They were subsequently taken to Tehran. Iran reported that the sailors are well. About 200 students targeted the British Embassy on 1 April 2007 calling for the expulsion of the country's ambassador because of the standoff over Iran's capture of 15 British sailors and marines. The protesters chanted "Death to Britain" and "Death to America". Speculation on the Iranians' motivations for this action ran rampant; with the Iranians under tremendous pressure on a number of fronts from the United States, the Revolutionary Guard Corps could have been responding to any one