The task before Gov. Mike Johanns, like the other 49 governors, was unenviable: Nebraska officials, already on high alert, were asked to go even higher. 

The FBI on Monday issued a new terrorism warning — the second this month — asking Americans to be on the highest alert for possible attacks this week, though no specific threat was identified.

``I am taking this warning very, very seriously,'' Johanns said.

Across the nation, governors struggled with how to respond after being notified of the new threat during a conference call with Tom Ridge, the nation's new homeland security director.

When the conference call ended, Delaware Gov. Ruth Ann Minner immediately made calls to the state police and the National Guard, said Minner spokesman Greg Patterson.

``We've been pretty much at a high state of alert since Sept. 11,'' he said. ``We will certainly be heeding the federal government's warning and will be more vigilant, if possible, than we have been.''

By week's end, New York Gov. George Pataki said more than 1,500 National Guard troops in and around New York City, from the World Trade Center site to airports and nuclear facilities, will be armed. Currently, only Guard troops at airports and nuclear plants are armed.

In the West Hollywood area of Los Angeles, where up to 250,000 people were expected for Halloween celebrations, police planned to have deputies patrolling by foot, car and horseback — security measures already planned before Monday's advisory.

Louisiana Gov. Mike Foster canceled a trip to Washington. ``It's not about my personal safety, it's about what would happen if I'm in D.C. and there is an attack and I have to get back from D.C.,'' Foster said.

Florida has no immediate changes planned for its security, but Gov. Jeb Bush will meet with law enforcement officials Tuesday to get an ``honest assessment'' of the state's security level, said spokeswoman Katie Baur.

Connecticut Gov. John G. Rowland ordered National Guard troops to begin patrolling nuclear facilities, and state police were put on their highest state of alert, with all troopers placed on standby.

The governor had not ordered any new security measures on Oct. 11 when the FBI said it had gathered ``certain information'' that additional terrorism attacks could occur within days.

``There were no specific targets mentioned in Connecticut or anywhere else in the nation,'' Rowland spokesman Dean Pagani said. ``But obviously it was serious enough that they would consider alerting all the governors.''

Montana Gov. Judy Martz said she would announce steps on Tuesday that the state plans to take in response to the FBI warning. ``As soon as we know what we're doing, we'll give you as much information as we can,'' she said.

Many other officials shared her concern — and frustration.

``Obviously, if you're at the highest state, it's hard to go higher,'' said Jim McDonald, spokesman for a company that operates the Palo Verde Nuclear Generating Plant, 50 miles west of Phoenix.