Following the recent attacks in Paris, some airlines are offering flexibility for travelers who are concerned about safety and would like to push back their trips.

Although most airlines are still flying to Paris as scheduled, they are generally willing to waive change fees for travelers who had previously booked flights to or from Paris. But many of the policies only offer leeway for people who had originally planned to travel by Sunday. Travelers with tickets beyond that date, including plans to spend Thanksgiving in the French capital, may be out of luck.

However, airlines are updating their policies and extending waivers as needed, so travelers should check with the company before making any changes. Travelers should also check with the State Department, which issues travel warnings and alerts after certain events. As of Wednesday, there were no notices relating to Paris, but the U.S. Embassy in Paris sent an emergency message to U.S. citizens in France, asking them to be vigilant.

Here is a look at some steps being taken by major airlines:

United Airlines is waiving change fees and any difference in airfare for customers who originally planned to travel to and from Paris between this past Monday and this coming Sunday and would like to reschedule their flights for travel by Nov. 30. Travelers would have to keep the same route and seating class as the original tickets. For travelers who would like to reschedule their Paris trips to travel after Nov. 30 or change their destination or departure altogether, the change fee still will be waived, but customers may need to pay for any difference in airfare. Travel must be rescheduled for within a year from when the first ticket was issued.

American Airlines is waiving change fees for people who bought their flight before last Friday and who were originally scheduled to travel to or from Charles De Gaulle Airport in Paris between this past Monday and this coming Sunday. They need to be flexible to travel by Dec. 15 to avoid the change fee. American is flying a full schedule to Paris, which includes six flights a day.

Delta is waiving change fees for travelers who had plans to travel to and from various cities in France, including Paris, Bordeaux, Nice and others. People originally booked to fly through those cities between this past Tuesday and this coming Sunday may have their change fee waived if they rebook to travel no later than Dec. 15. Those originally booked to travel to and from the affected cities between last Friday and this past Monday may have the fee waived if they book their new flight for travel no later than Sunday.