Counter-terrorism expert Richard Barrett has raised the possibility that the Woolwich attackers may have been "copycats" of the Boston bombers.
I don't think we have seen much of this in terms of attacks on armed service personnel in the UK before.
It may be that this is a copycat after the Boston bombings. That two individuals could cause a lot of mayhem is maybe more of an inspiration than attacking soldiers.
The former United Nations co-ordinator for the al Qaida and Taliban monitoring team, who has served with MI5 and MI6, said it was clear the attackers wanted to "explain" their actions:
It looks like an attack which has certainly been done for effect. The way that they are hanging about and wanting to be arrested and explain what they were doing fits a pattern of people who want to send a message.