One of the largest policing operations in recent years is preparing to start in London to provide security for the State visit of US President George Bush. BBC News Online explains what will happen to the capital - and what protesters will be allowed to do.
What are the plans for President Bush's visit?
President George W Bush begins a three-day state visit to the UK on Wednesday 19 November.
He will arrive the day before and participate in a private welcome at Buckingham Palace.
On the 19th he will be formally welcomed by the Queen in the morning before meeting with Tory leader Michael Howard and Lib Dem leader Charles Kennedy.
In the afternoon, President Bush will deliver a speech at Banqueting House on the transatlantic alliance and America's strategy.
After this he is due to meet the families of British victims of September 11.
In the evening Mr Bush and the First Lady will attend a state banquet in their honour at Buckingham Palace.
On Thursday 20 November the President will visit the Tomb of the Unknown Warrior, tour Westminster Abbey, and meet British soldiers who fought in Afghanistan and Iraq, and their families.
The afternoon sees Mr Bush at Downing St with Tony Blair. They will hold a roundtable meeting on HIV/AIDS, attend a working lunch and meet with the media.
That evening, the President and the First Lady will host a reciprocal dinner for the Queen at the US Ambassador's residence, Winfield House.
On Friday 21 November, Mr Bush will attend the Queen's official farewell before heading to Sedgefield, Tony Blair's constituency, where they will have lunch with his constituents.
The President and First Lady will leave for Washington on Friday evening.
Some 5,000 police officers are going to be on duty in the capital throughout the visit.
So what kind of protests are we expecting?
The principal organisers of the demonstrations are members of the coalition which led the "Stop the War" marches before the conflict.
In February, at least 750,000 people marched against the war, although it is not expected a similar number will turn out this time.
However, what has been unclear until now is how the police were planning to handle protests, given the US administration's heightened sense of alert.
What has been going on behind the scenes?
Reports earlier this week suggested the US had demanded the Metropolitan Police shut down parts of central London.
But senior police officers have made it clear that this will not happen because their job is to balance the president's security with the right to protest.
So London will not be closed down?
Not at all, says the Metropolitan Police.
Deputy Assistant Commissioner Andy Trotter insists the police have not come under any pressure from the White House, Buckingham Palace, Downing Street or anywhere else.
In a briefing on Wednesday, he stressed Sir John Stevens, Commissioner of the Metropolitan Police, had the final say on the capital's security - and not the US secret service. And that meant there would be no "exclusion zones".
"It is our intention to facilitate lawful protest," said Mr Trotter. "We must be one of the most co-operative police forces [in the world] as we facilitate 3,500 demonstrations every year."
But what about keeping protesters away from the president?
One of the concerns of protesters is officers would confiscate banners in similar circumstances to the October 1999 visit of China's President Jiang Zemin.
Sir Paul Condon, the then head of the force, later said some of his officers had acted in error when they prevented demonstrators from making their voice heard as the Chinese delegation passed by.
Today, the force says it has reviewed how that visit was handled and "refined" tactics to balance security and the right to protest.
So what does this mean in practical terms?
Asked whether protesters would come close to President Bush, Mr Trotter said: "There is no intention to spare anyone embarrassment [of public protests]. But we must be really aware of the security issues."
So, protest marches will be banned from Whitehall and Parliament Square (an order usually in place when Parliament is sitting) and the force will prevent large crowds blocking the president's movements.
Police officers are likely to close and open individual roads on a rolling basis to allow the president's cavalcade to move around.
But the entourage could "quite easily" pass peaceful protesters lining the pavements as police would recognise their right to be there.
Do the police believe there is any specific threat against the president?
The Metropolitan Police says it is handling the event in line with its heightened level of alert - but there is no specific intelligence of a threat.
It has drawn a comparison with May Day protests of recent years.
At each of those, the force says there has been intelligence of planned violence. So far, there has been no such expectation of violence for the president's visit.
However, Mr Trotter stresses officers will be authorised to use wide-ranging anti-terrorism powers to stop and search protesters.
The same powers were unsuccessfully challenged in the High Court after they were controversially used against arms fair protesters in September.
So we are expecting a peaceful if noisy few days?
The Metropolitan Police says that it hopes protests will be peaceful and law abiding. It has praised the leaders of the Stop the War movement for how they have worked with the police so far.
Mr Trotter said February's huge anti-war march had been so well planned and marshalled there had been fewer arrests in central London than on an average Saturday - and it was hoping for a similar situation again.