UK domestic spy chief warns of possible return of Iran state-sponsored terror By Msnbc.com's F. Brinley Bruton and NBC News' Kier Simmons LONDON -- Iran may return to a campaign of state-sponsored terrorism, the head of MI5, the UK's internal counter-intelligence and security service, said during a wide-ranging talk in London's financial center late Monday. NBC News has also learned that the British Security Service, MI5's official name, has substantially expanded its team dealing with possible terrorism threats from Iran. "In parallel with rising concern about Iran's nuclear intentions, we have seen in recent months a series of attempted terrorist plots against Israeli interests in India, Azerbaijan and elsewhere," Jonathan Evans, director general of MI5, said at a lecture here at the official residence of the Lord Mayor of London, Mansion House. The U.S. authorities last year uncovered a plot by the Iran's Islamic Revolutionary Guard Corps to mount an attack on the Saudi Ambassador in America, and of course the IRGC leads straight back to the Iranian leadership. Just days after the U.S. says it foiled a shocking plan - allegedly orchestrated by Iran -- to assassinate a Saudi diplomat at a Washington, D.C., restaurant, Secretary of State Hillary Clinton discusses the "dangerous escalation" in Iran's support for terrorism with TODAY's Savannah Guthrie. Bangkok blasts wound Iranian attacker, 4 others While Iran insists that its nuclear program is peaceful and not aimed at making weapons as suspected by Western nations, tensions are high in the region. A recent round of nuclear talks between Iran and world powers in Moscow failed to secure a breakthrough, heightening fears Israel might take unilateral military action to curb Iran's nuclear activities, and thus unleash a violent response from Tehran. "So a return to state-sponsored terrorism by Iran or its associates, such as Hezbollah, cannot be ruled out as pressure on the Iranian leadership increases," Evans said during his first public statement in two years. Hezbollah is a Lebanese Shiite militant group. US officials vow to hold Iran accountable for alleged assassination plot During the annual defense and security lecture, titled "The Olympics and Beyond," Evans said preparations for the 2012 Summer Olympics and Paralympic Games have been thorough. But he said the 2012 Summer Games remain a target and will be the center of the world's attention. No doubt some terrorist networks have thought about whether they could pull off an attack. But the Games are not an easy target and the fact that we have disrupted multiple terrorist plots here and abroad in recent years demonstrates that the UK as a whole is not an easy target for terrorism," he said. In February, British police, fire and ambulances tested their ability to manage should terrorists strike the Games. NBC's Duncan Golestani reports. At London Olympics, dogs have sniffed out a key anti-terror role The threat level was at "substantial," Evans said, which meant that an attack was a strong possibility. Terrorism will outlast the Games, he said, noting that there had not been a successful al-Qaida related strike on the UK since the July 7, 2005, subway and bus attacks in London that killed 54, including four bombers, and injured more than 700. However, there had been a "credible terrorist attack plot about once a year since 9/11 -- and before, since the first al-Qaida inspired plot here took place in 2000 -- a year before 9/11." Assistant Commissioner Chris Allison of the UK Metropolitan Police will head up the security effort for the 2012 Olympics in London. He says the games will be the UK's largest peacetime security operation in the nation's history. Report: Fake bomb exposes London Olympic security The MI5 chief also warned businesses not to become complacent about malicious activity in cyberspace. "The extent of what is going on is astonishing -- with industrial-scale processes involving many thousands of people lying behind both state-sponsored cyber espionage and organized cyber crime," he said. Evans also touched on the Arab Spring, which he said "offers the long term hope of a more pluralistic, democratic and flexible system in the Arab world that will respond to the aspirations of its population." The swift and sometimes violent change in the Arab world also presented a problem, however, as parts of the region become more "permissive" environments for al-Qaida extremists. Said Evans: A small number of British would-be jihadis are also making their way to Arab countries to seek training and opportunities for militant activity, as they do in Somalia and Yemen. Some will return to the UK and pose a threat here. This is a new and worrying development and could get worse as events unfold. So we will have to manage the short term risks if there is to be a longer-term reward from the Arab Spring.