Troops, Embassies on Alert Amid Attacks

American installations around the world stepped up their security measures, and military forces re-deployed in the wake of today's wave of terrorist attacks on targets around the nation.

Four passenger planes were apparently hijacked today in acts of terrorism. Two crashed into the twin towers of New York City's World Trade Center, and one crashed into the Pentagon outside the nation's capital. The last aircraft crashed in western Pennsylvania.

The aircraft carriers USS George Washington and the USS John F. Kennedy left their ports today, headed for the coast off New York to protect it from any further attack.

Five other ships also put to sea — guided-missile destroyers and frigates — and the USS Comfort left its port in Baltimore with a medical crew from Bethesda Naval Hospital, presumably to help in rescue efforts in New York.

The National Guard mobilized all its troops in the New York City area as well.

In Washington, authorities deployed soldiers, including a regiment of light infantry.

Threatcon Delta

American military installations abroad said they were at a high level of alert.

Fighters, airborne radar and refueling planes around the nation were scrambled, all unnecessary military flights were canceled, and North American Aerospace Defense Command was on its highest alert.

Meanwhile, at military bases across the country, officials said only essential military personnel would be given access.

NATO and SHAPE, NATO's operational school in Oberammergau, Germany, said they had not received any specific threat, but they had evacuated all nonessential personnel as a protective measure.

NATO ambassadors in Brussels, Belgium, planned to hold a meeting to discuss the attacks.

The U.S. European Command in Stuttgart, Germany, said all U.S. forces in Europe had "taken increased forces protection measures" and had gone to Force Protection Level Delta, among the highest levels of alert.

The U.S. permanent air fighter base in Aviano, Italy, which receives its orders from Stuttgart, confirmed that it was on a Delta state of alert.

Information was unavailable for the U.S. Navy's Fifth Fleet, based in Manama, Bahrain.

"We are not releasing any information at this juncture. We have no comments to make," an official with the U.S. Navy Central Command said.

The aircraft carrier USS Enterprise, which was due to come home from the Persian Gulf, was ordered to remain in the area indefinitely. A second carrier, the USS Carl Vinson, remains in the area as well, an official told The Associated Press.

One of the Fifth Fleet's boats, the guided-missile frigate USS Nicholas, left Malta early today after arriving Monday for four-day visit.

The U.S. Embassy in Valleta, the Maltese capital, had no comment. Security was increased around the British aircraft carrier HMS Illustrious, which was also in Valletta harbor.

Words of Caution

The state of American embassies abroad varied depending on the area.

In Europe, things were a little less dire. In London, a press officer told ABCNEWS the U.S. Embassy expects to be open for "business as usual" on Wednesday.

Plans for the American embassies in Paris and Rome were still to be determined. Embassy officials reportedly have told Americans to keep a high state of vigilance and take appropriate measures to increase security and decrease vulnerability.

In the Middle East, officials were taking stronger steps. The embassy in Tel Aviv, Israel, was evacuated. It remained to be determined if it would be reopened on Wednesday.

In Cairo, Egypt, the embassy sent a warning to U.S. citizens urging them not to send their children to school on Wednesday.