Plane Terror Plot 'The Real Deal'

British authorities said Thursday they had thwarted a major terrorist plot to simultaneously blow up several aircraft heading to the United States by using explosives smuggled in hand luggage — averting what police described as "mass murder on an unimaginable scale."

Britain said 21 people were arrested overnight, including the alleged "main players" in the plot. The scheme involved 10 flights, one U.S. counter-terrorism official said.

CBS News reports that four arrests were made in Pakistan in recent days, two of which are "very important."

Officials tell ABC News that twenty-two of the arrested suspects are believed to be of Pakistani descent. One is Bangladeshi, and another is of Iranian descent, according to the officials.

Five of the suspected London terrorists are still at large and are being urgently hunted, U.S. sources who have been briefed on the airplane bombing plot told ABC News.

"This country is safer than it was prior to 9/11. We've taken a lot of measures to protect the American people, but obviously we're not completely safe," President Bush said Thursday from an airport tarmac in Wisconsin. "It is a mistake to believe there is no threat to the United States of America."

The president also laid the blame for the foiled attack squarely on al Qaeda-type terrorism.

"This nation is at war with Islamic fascists who will use any means to destroy those of us who love freedom, to hurt our nation," Mr. Bush said.

Pakistan intelligence helped British security agencies crack the terrorist plot, a government and an intelligence official said Thursday. The intelligence official said an Islamic militant arrested near the Afghan-Pakistan border several weeks ago provided a lead that played a role in "unearthing the plot," that helped authorities arrest suspects in Britain.

French Interior Minister Nicolas Sarkozy said in Paris that the plotters "appear to be of Pakistani origin."

The U.S. issued its highest terrorism alert ever, red, for commercial flights from Britain to the United States and raised the threat level for all domestic and international flights. All other flights, including all domestic flights in the United States, were put under an orange alert, one step below the highest level.

"No liquids or gels of any kind will be permitted in carry-on baggage. Such items must be in checked baggage. This includes all beverages, shampoo, sun tan lotion, creams, toothpaste, hair gel and other items of similar consistency," a Homeland Security statement cautioned passengers.

Homeland Security Secretary Michael Chertoff said the terrorists planned to use liquid explosives disguised as beverages and other common products and detonators disguised as electronic devices. They planned to combine the products once the planes were aloft to create and detonate explosive devices. Sources tell CBS News correspondent Jim Stewart that these chemical bombs would have been set with timers to go off simultaneously.

Stewart reports that the flights from London to New York were targeted and involved flights on U.S. carriers heading to New York's John F. Kennedy, Washington Dulles, Miami International and Los Angeles International airports aboard U.S. carriers.

U.S. counterterrorism officials tell CBS News correspondent Sheila MacVicar that United, American and Continental Airlines — all U.S. carriers — were targets of the plot.

"This is not a case of wannabes fantasizing about an attack. We believe it was the real deal. To target multiple airlines with such a plan requires a sophistication that strongly points to al Qaeda," a senior U.S. official told Stewart.

White House spokesman Tony Snow said President Bush and British Prime Minister Tony Blair held a lengthy teleconference on the matter Sunday and spoke again Wednesday by phone, Snow said.

"There were some signs," Snow said. "They thought it was time to move," he said of British authorities.

Chertoff said the plot is "suggestive of an al Qaeda plot," and that the plotters were in the final stages to execute all elements of this plan. He added that there was no indication of plotting in the United States and that it was unclear whether the alleged plot was linked to the upcoming fifth anniversary of the Sept. 11 attacks.

London Deputy Commissioner Paul Stephenson says the arrests were made in London, its suburbs and in Birmingham, and that searches continue in a number of locations. "We are confident that we've prevented an attempt to commit mass murder on an unimaginable scale," Stephenson said.

Britain's home secretary, John Reid, said about a dozen of the suspects were "very close" to succeeding in the plot, which he describes as "significant" and designed to cause loss of life. The threat level in England has, for the first time ever, been raised to critical. That means the threat of an attack is imminent, MacVicar reports.

Peter Clarke, head of the Metropolitan Police anti-terrorist branch, said surveillance had been carried out for months before police arrested the 21 people overnight. Sources tell Stewart that several of the 21 suspects picked up may not have been actual bombers, but people with material knowledge of the plot.

"We have been looking at meetings, movements, travel, spending and the aspirations of a large group of people," Clarke said. "All the arrests were made on suspicion of the commission, preparation or instigation of acts of terrorism."

British Airways canceled all flights between Heathrow Airport and points in Britain, Europe and Libya for all of Thursday. Extra security measures in place at airports leaving Britain include a ban on carry-on luggage, including purses too big to fit in a passenger's pocket. Passengers are only allowed to take personal items — such as passport, eyeglasses and cash — if they are in see-through plastic bags.

A British police official says the suspects are "homegrown," though it was not immediately clear if all of the people in custody are British citizens. The official says police investigating the foiled attack are working closely with the South Asian community.

"It's disrupting huge commerce, disrupting plans here in the United States and abroad, and they would not have gone with precautions like this unless it was a very serious threat," said Christopher Whitcomb, a terrorism expert for CBS News. "It could have been catastrophic."

Rodolfo Mendoza, a police intelligence official in the Philippines, said the style of attach bears a striking resemblance to approaches al Qaeda has used in the past.

A scheme by al Qaeda terror mastermind Ramzi Yousef was set to use liquid explosives to blow up a dozen airliners in 1995 as they flew across the Pacific to U.S. destinations, including Los Angeles, San Francisco, Honolulu and New York. That 1995 plot was also thwarted.

Blair's office said in London that the prime minister, vacationing in the Caribbean, briefed President Bush, vacationing at his ranch near Crawford, Texas, on the situation.

"The United States and the United Kingdom are fully united and resolute in this effort and in our ongoing efforts to secure our respective homelands," said Chertoff.

U.S. intelligence, particularly the CIA, has been working closely with Britain on the investigation, which has been ongoing for months, the second official said.

"We cannot assume that this threat has been completely thwarted," Chertoff said. "There's sufficient uncertainty as to whether the British have scooped up everybody."

As a result of the plot, new security precautions have been put into effect at airports in both England and the United States. Guards armed with rifles stood watch in several airports, and the governors of California, New York and Massachusetts said they were sending National Guard troops to bolster security.

Precautions are in place throughout Asia and Europe as well. Security at Charles de Gaulle airport in Paris are on red alert, the second-highest level on the French system, CBS News' Elaine Cobbe reported. There is increased security around British Airlines. Airlines in South Korea, Singapore, Japan and Australia imposed new restrictions on carry-on and other luggage for jets in accordance with requests from American and British authorities.

Britain's Transport Secretary Douglas Alexander, speaking at a news conference in London, asked air travelers to show patience and understanding of the new rules, which he says will be in effect "as long as the situation demands."

Heathrow, the busiest airport in Europe, was closed to most European flights Thursday morning. The block on incoming traffic applies to flights of three hours or less, affecting most of the incoming traffic from Europe, according to an airport spokesman.

Air France canceled all morning flights to Heathrow, saying it acted because the airport is "saturated." The French interior minister canceled his vacation to return to Paris for an urgent meeting on security with police and intelligence officials.