WASHINGTON/KABUL (REUTERS) — The United States launched a second round of nighttime air strikes on Afghanistan Monday in its war against terrorism, and reinforced its home front against a possible new assault by Islamic militants after last month’s attacks that killed nearly 5,600 people.

Thousands of additional armed police and National Guard troops patrolled U.S. airports and train stations, former Pennsylvania Gov. Tom Ridge was sworn in as the new Cabinet officer in charge of homeland defense, and the U.S. Coast Guard moved to its highest state of alert since World War Two.

Nuclear power plants, airports and U.S., British and Israeli diplomatic missions were among sites around the world where security was tightened amid concerns over reprisals. Britain stepped up the guard at Queen Elizabeth’s Buckingham Palace and at the Houses of Parliament.

Meanwhile, military jets scrambled Monday to escort a commercial jetliner with 162 people on board to a safe landing in Chicago after passengers helped the crew subdue a mentally ill man who forced his way into the cockpit, setting off a scare that another Sept. 11-style hijacking might be in the offing.

Sonic booms set off by the two speeding military jets above Chicago’s northern suburbs rattled nerves, though the incident aboard the American Airlines jet bound for Chicago from Los Angeles was not linked in any way to the hijacked plane attacks on New York and Washington.

NEW SENSE OF VULNERABILITY

The FBI said a 31-year-old man with a history of mental illness was subdued by a co-pilot and another crewmember with the help of several passengers.

Americans have a new sense of vulnerability since the Sept. 11 attacks by hijacked airliners, which destroyed New York’s World Trade Center and damaged the Pentagon, and authorities are investigating a second case of exposure to anthrax, a disease often mentioned as a potential biological warfare agent.

The FBI has asked law enforcement agencies across the country to operate at the highest possible state of alert for “any act of terrorism or violence” domestically.

The FBI said it was urgently investigating the case of a co-worker of a Florida man who died of anthrax last week in what health officials then described as an isolated case and not a biological attack.

The second man has tested positive for exposure to the extremely rare disease. Both men worked at the Florida company that publishes the supermarket tabloids National Enquirer and Star.

“The FBI is taking this very, very seriously,” Florida Gov. Jeb Bush, the president’s brother, told reporters. “This is the new reality. We’ve talked about these biological and chemical agents being part of some terrorist arsenal, and whether it is in this case or not, we have to be prepared for it. It needs to be a much higher priority than it has been in the past.”

NIGHT ATTACKS

As night fell in Afghanistan, U.S. forces resumed their pounding of strategic targets designed to weaken Afghanistan’s ruling Taliban and disrupt the al Qaeda network controlled by Osama bin Laden, the Saudi-born militant who the United States believes masterminded the attacks.

At least four bombs were dropped late Monday in the Afghan capital of Kabul and were believed to have hit the airport and a hill housing the city’s main television antennae. The city was plunged into darkness for a second consecutive night.

The first strikes damaged airports and strategic buildings and killed a handful of people, according to the Taliban.

Monday’s attack also struck the northern cities of Mazar-i-Sharif and Kunduz, the Afghan Islamic Press reported.

The United States also said Monday that it might have to launch military strikes on other nations and groups beyond Afghanistan.

“We may find that our self-defense requires further actions with respect to other organizations and other states,” U.S. Ambassador John Negroponte said in a letter to the 15-nation U.N. Security Council.

But Britain, Washington’s closest ally in the military campaign launched on Sunday, quickly insisted the current action was limited to targets in Afghanistan.

“The agreement at the moment is that (the strikes) are confined to Afghanistan. That is where the problem is,” British Foreign Secretary Jack Straw said in Luxembourg when asked about the U.S. statement.

NOTHING TO FEAR BUT FEAR ITSELF

Mayor Rudolph Giuliani of New York kicked off the annual Columbus Day parade Monday, saying the event was a vital symbol that showed New York could move forward despite the attack that reduced the World Trade Center’s twin towers, themselves a potent symbol of American prosperity, to rubble.

“We’re not going to let terrorists hinder us; we’re not going to let any fears that people might have hinder us. We’re going to move ahead and celebrate a very important American holiday, Columbus Day,” Giuliani told reporters at the event, which went ahead while the city stepped up security.

As New York marked Italian explorer Christopher Columbus’ landing in America, Defense Secretary Donald Rumsfeld and Air Force Gen. Richard Myers, chairman of the Pentagon Joint Chiefs of Staff, said initial strikes against 31 Taliban air defense and other targets and guerrilla training bases in Afghanistan on Sunday appeared to have been successful.

Myers and Rumsfeld said the strikes had severely damaged Taliban air defenses, but they had not been completely destroyed and there was no indication yet that military communications had been disrupted on the ground.

The general said Taliban early warning radar, ground forces, command and control facilities, airfields and aircraft, as well as al Qaeda’s infrastructure, were hit on Sunday and Monday.

Canada said it would contribute six ships, the same number of aircraft and a special commando unit to the U.S-led military coalition and the former Soviet republic of Tajikistan, Afghanistan’s northern neighbor, said it was prepared to let U.S. forces use its air bases for military action.

French Defense Minister Alain Richard said French forces would help Washington wherever needed. “It could be special forces, air facilities and added naval support,” he said.

FIRST RAIDS HIT STRATEGIC TARGETS

Initial estimates from across Afghanistan had placed the death toll at 20, but Deputy Health Minister Mohammad Abbas later said the toll was about eight.

Still, thousands of Kabul residents, fearing more attacks after three waves of bombing and missile strikes shattered the silence of the night in their war-shattered city, packed up what they could and fled the capital as dawn broke.

The world reacted to the strikes with unanimous condemnation of terrorism, but as U.S. allies welcomed the strikes, some Muslim leaders said it was Washington that was now playing the terrorist. In Pakistan, Afghanistan’s southern neighbor, anti-U.S. protesters burned cars and a U.N. office.

President Bush and key members of his security team have said new attacks on U.S. soil are possible.

In a televised broadcast after the world’s most modern arsenal unleashed its might on one of its least developed countries, bin Laden warned Americans they would never be safe until Palestine was at peace and U.S. forces stationed in Saudi Arabia had left.

TALIBAN CALLS JIHAD

The Taliban cabinet endorsed on Monday a call by a meeting of clerics to declare a jihad, saying the Afghan people would sacrifice all for honor.

Meanwhile, anti-U.S. wrath gripped Pakistan’s cities. Pakistani police opened fire on anti-U.S. demonstrators who brandished pictures of bin Laden and burned cars and a U.N. office in protests against the strikes. One person was killed.

As Pakistan’s military ruler, General Pervez Musharraf, assured the world there was no serious opposition to his pro-American policy, protesters rampaged through cities to vent their anger at attacks on Afghanistan that he assisted.

Palestinian police shot dead two protesters and 40 were wounded in clashes in support of bin Laden on Monday, the first time Palestinians were killed by their own security forces since the start of the anti-Israel revolt.

In an apparent carrot-and-stick approach, less than nine hours after Sunday’s strikes began, two U.S. C-17 cargo planes dropped 37,000 humanitarian food packages to displaced Afghan refugees facing starvation in remote areas of that country.

Taliban officials said bin Laden and his spiritual leader, the reclusive one-eyed Mullah Mohammad Omar, were unhurt in the raids.

Bin Laden, 44, who is from a wealthy Saudi family, has been defying U.S. efforts to capture or kill him for years. Since 1996, he has been living under the protection of the Taliban in Afghanistan in a remote mountain redoubt.