London police are mounting their biggest-ever security operation as U.S. President George Bush prepares to arrive Tuesday for a state visit.
About 14,000 police will be on duty during the president's four-day visit to Britain. Several hundred American agents will also guard Mr. Bush.
But a lone anti-Bush protester managed to elude the police cordon and scale the front gate at Buckingham Palace, where Mr. Bush will stay as the official guest of Queen Elizabeth II. The demonstrator hung an American flag upside down on the gold-plated gate.
Police officials estimate the security operation will cost about $9 million. Metropolitan Police chief John Stevens says the level of security will be "unprecedented."
Coincidental to the Bush visit, Britain has increased its terrorist threat alert, amid reports that authorities are concerned about a possible attack by the al-Qaida terrorist network.
Another challenge for the police will be major anti-Bush street demonstrations. Police plan to restrict marching routes to keep protesters away from the president.
On the eve of the Bush visit, British Prime Minister Tony Blair told a business group he stands by the decision to invite the president to Britain.
"This is the right moment for us to stand firm with the United States of America in defeating terrorism wherever it is and delivering us safety from what I genuinely believe to be the security threat of the early 21st century," said Mr. Blair. "And now is not the time to waiver, now is the time to see it through."
As the prime minister spoke, the London-based Stop-the-War Coalition delivered petitions to his office signed by what activists said were 100,000 people demanding Mr. Blair withdraw the invitation.
A coalition leader, Lindsey German, says tens of thousands of demonstrators plan to protest against Mr. Bush and Mr. Blair.
"I think it is rather unrealistic to invite the most unpopular world leader at the end of the most unpopular war for decades," said Ms. German. "And I think if Tony Blair had any sense, if he does not want to have a political crisis and if he wants London to be free from disruption, the easiest thing he could do is rescind the invitation. If he does not there will be very big demonstrations."
The biggest rally is scheduled Thursday for London's Trafalgar Square, when protesters plan to pull down an effigy of President Bush in a symbolic re-enactment of the toppling of Saddam Hussein's statue in Baghdad in April.
Mr. Bush has said that the protests will not bother him, and he looks forward to visiting a country where people can have so much freedom.