WASHINGTON -- Barricaded streets, helicopters buzzing overhead and heavily armed police officers patrolling federal buildings: This is how the heart of the nation's capital appears on the eve of war with Iraq and a heightened terrorism alert.
But the heavy security fades the farther one goes from downtown, and many area residents and visitors seem fatalistic about the possibility of suicide bombings or other retaliatory attacks.
Asked if he was afraid, tourist Scott Hall of Valparaiso, Ind., shrugged: "I think concerned is a better word. I haven't really noticed anything too different. But I'm always aware."
In fact, one of the greatest security-related inconveniences in Washington this week is also a reminder of what makes this country unique.
It is the closing of a major downtown artery, the six-lane Constitution Avenue, while a tobacco farmer from North Carolina sits on a tractor he drove into a shallow pond on the Mall. He wears a military medic's helmet and waves an American flag upside down in the traditional sign of distress.
Dwight Watson, 50, of Whitakers, N.C., has held more than 100 officers and a SWAT team in an armored personnel carrier at bay since Monday, claiming to have explosives.
He is apparently upset about government controls and taxes and cigarettes.
"I'm going to get my message out or die trying," Watson told the Washington Post. "I've got the rest of my life to stay right here. I'm not going anywhere."
About noon Monday, Watson drove a jeep pulling a trailer carrying a tractor and a motorcycle into the pond near the Vietnam Veterans Memorial and the Lincoln Memorial.
"We don't know what's contained in those vehicles, so we're prepared for the worst," said Sgt. Scott Fear, a U.S. Park Police spokesman. "We believe he's dangerous, absolutely."
Police have communicated with Watson via cell phone but did not say whether he had made any demands or if they believe he does, as he claimed, have ammonium nitrate, the same fertilizer material Timothy McVeigh used to blow up the Oklahoma City federal building in 1995.
Homeland Security Secretary Tom Ridge said the incident does not appear "in any way connected with the kind of terrorism" authorities expect from Islamic militants in response to an invasion of Iraq.
As long as Constitution Avenue is not needed as an evacuation route, Fear said, police are "going to be patient with him and we're going to make sure that human life and safety is No. 1."
The closure of Constitution Avenue and eight other major streets for the incident kept traffic snarled and Potomac River bridges backed up.
Meanwhile, the threat of terrorism kept Virginia Avenue near the State Department and streets around the Capitol closed, further aggravating motorists.
Most of the preparations for wartime attacks were being made out of public view.
The Federal Aviation Administration is once again requiring all pilots to file flight plans to land at Washington-area airports, which have stepped up random searches and identification checks.
And the District of Columbia police activated a system of 14 surveillance cameras around the city.
The Agriculture Department asked food processors and farmers to increase scrutiny of vehicles and people entering their premises to guard against attempts to poison the food supply.
Visitors to the Justice Department were told to allow extra time for security procedures.
Still, Washingtonians seemed to have become a bit numb to terror alerts. Joggers enjoying warm spring weather made their way down the Mall past the police tape keeping them away from the tobacco farmer's potential explosives.
Outside the Capitol, Sen. George Allen, R-Va., greeted Sen. Patrick Leahy, D-Vt. Allen had to raise his voice to be heard over the sound of jackhammers building a new visitors center.
"I don't have any particular worry," Allen said. "The people I'm worried about most are the men and women in our military."
Nearby, as a Capitol Police officer stood at an entrance to the building with a military-style rifle over his shoulder, the Virginia senator said, "If a bullet's gonna hit you, it's gonna hit you."
Monday evening, shortly after President Bush's televised address to the nation about Iraq, Homeland Security Secretary Ridge announced the national terror alert would be raised a notch, from an elevated to a high risk of attack -- yellow to orange.
In a statement, Ridge said unspecified "suspicious activity" near military facilities, ports, waterways, bridges, dams and power generating facilities had contributed to the decision to raise the threat level.
He announced a plan, dubbed "Operation Liberty Shield," to enhance security. The plan includes mandatory detention of asylum applicants from countries where the al-Qaida terrorist network is known to operate and the questioning of thousands of Iraq natives in America.
As for detention of asylum seekers, Ridge said, "We want to make absolutely certain during this period of time you are who you say you are." He would not estimate how many asylum seekers might be detained.
Authorities said there are no plans at this time to raise the alert to its highest level -- a red alert -- indicating a severe threat.
Monday was the third time authorities have put the nation on high alert for terrorism.
The country was at that level for two weeks last year surrounding the anniversary of the Sept. 11, 2001, attacks and again from Feb. 7 to 27 after intelligence agencies picked up increased electronic chatter among suspected terrorists about a possible attack.
Citizens who want more information about preparing for a terrorism attack can consult a Homeland Security Department Web site, http://www.ready.gov/. The department also offers a toll free number for advice, 1-800-Be-Ready.