If you’re traveling this Thanksgiving holiday, brace yourself.

Wait times at U.S. airport security checkpoints were already up this year as passenger counts grew and the Transportation Security Administration imposed more thorough screening protocols.

Now, after terrorist attacks in Paris and a suspected airliner bombing in Egypt, people enduring the normal chaos of the busy travel period will also face a gauntlet of bomb- sniffing dogs, extra armed officers and the near-certain prospect of even longer lines, according to travel groups, airlines and airports.

“People should come in with an expectation to give themselves extra time,” said Frank Cilluffo, director of the Center for Cyber and Homeland Security at George Washington University. “Patience will be in high demand.”

While there are no specific threats indicating terrorists intend to strike during the holiday travel surge, U.S. and local authorities have been hiking security measures as a precaution, Homeland Security Secretary Jeh Johnson has said in recent days.

LAX Security

“There’s going to be a stepped-up security presence, more police in uniform and more police dogs,” said Bob Blumenfield, a Los Angeles city councilman who is chairman of the committee overseeing the city’s airport. “There will also be a lot they don’t see that’s going on behind the scenes.”

That goes for travel by passenger rail as well, Amtrak spokesman Craig Schulz said. “Passengers might notice an increased police presence at stations, on trains and along the tracks,” he said.

The TSA issued a statement urging travelers to review its rules, such as the ban on carrying items with more than 3.4 ounces (100 milliliters) of liquid, to prevent unnecessary delays during screening. “As we experience every year during the busy holiday season, passengers can expect to see some increase in wait times,” the TSA said in the e-mailed statement.

Early Arrival

Atlanta’s Hartsfield-Jackson International Airport, the world’s busiest in terms of passengers, is advising people to arrive 2 1/2 hours before flights during peak travel days over the next week, spokesman Reese McCranie said. Atlanta-based Delta Air Lines Inc. is going one better: it urges international travelers to arrive with 3 hours to spare.

With an improving economy and lower fuel prices, the number of people hitting the road this year will be the most in years, according to forecasts. AAA, the group promoting auto travel, predicts 46.9 million people in the U.S. will venture more than 50 miles (80 kilometers) from home, the highest since 2007.

Airlines for America, the trade group for most large carriers, estimated 25.3 million people will fly on U.S. carriers from Nov. 20 through Dec. 1, a 3 percent increase over 2014.

There will be more airline seats available on Nov. 29, the Sunday after the turkey carving festivities, than any day in 2015, according to tracking website FlightAware.com. Wednesday and Monday, Nov. 30, will also be busy, but more akin to a bustling Friday during the summer, according to FlightAware.

Islamic State

The holiday rush comes as the Islamic State, a Sunni Muslim group fighting to control territory in Iraq and Syria, has unleashed multiple attacks, including a coordinated wave of shootings and bombings in Paris on Nov. 13 that killed 130 people. The group took credit for placing a bomb on a Russian jet that blew up over Egypt on Oct. 31, killing 224.

Brussels authorities have locked down their city this week, fearing they are the target of an other attack. IS has also threatened to take the fight to the U.S.

The U.S. State Department issued a warning to international travelers Monday, saying Islamic State and other terrorist groups continue to plan attacks. It urged people to avoid large crowds and to “exercise particular caution during the holiday season and at holiday festivals or events.”

So far, there’s no credible threat of a Paris-scale assault in the U.S., according to FBI Director James Comey. Even so, authorities are watching closely for home-grown extremists who may attempt a copycat attack, a concern compounded during peak holiday shopping and travel seasons, Comey said.

NYC PD

Earlier this week, New York City’s police department for the first time deployed a special counter-terrorism team of more than 500 officers. The department has about 1,500 officers — out of 35,500 — assigned to combat terrorism. The new, heavily- armed unit is intended to be a rapid-reaction force in the event of a terrorist attack, NYPD Commissioner William Bratton said.

Heavily armed police and National Guard troops have been posted at bridge and tunnel crossings and inside transit facilities, while mobile units patrol throughout the city. Other teams guard iconic tourist attractions such as Times Square, religious institutions and the French consulate in Manhattan.

In the Washington region, the transit police force is conducting increased patrols on its trains and buses, adding sweeps by canine units and expanding the random screening for explosives. U.S. Capitol Police, who protect Congress, are monitoring events in Paris and there may be additional patrols, spokeswoman Kim Schneider said.

As the TSA has faced charges earlier this year that its screeners missed 96 percent of explosives and weapons during tests, security checkpoint wait times at large airports have increased.

Full Screening

The agency has also been making more passengers undergo more time-consuming full screening instead of randomly selecting them for the streamlined process reserved for people who have had their backgrounds checked, it said in a statement. At the same time, TSA has had to handle an eight percent increase in the number of passengers this year compared to last, according to a statement.

As a result, the number of passengers waiting as long as 20 minutes in line in Atlanta’s airport jumped from 23.9 percent from May 4, 2014, through Sept. 30, 2014, to 33.5 percent in the same period this year, according to TSA. Three of the four large airports surveyed has similar increases, according to the agency.

–With assistance from Michael Sasso, Del Quentin Wilber and Henry Goldman.

This article was written by Alan Levin, Mary Schlangenstein and Jeff Plungis from Bloomberg and was legally licensed through the NewsCred publisher network.

Photo Credit: Austin Brislain, of Atlanta, checks in for a flight to Indianapolis at Hartsfield-Jackson International Airport. David Tulis / Associated Press