Which airline is the best in the business?

The U.S. airlines have been forced to re-evaluate their business models following the deadly Paris attacks, with some airlines looking to the past and others looking to what they say is a global economy.

Here’s what you need to know about the industry, its new and old players, and the impact of terrorism on the future.

Air France (AF) says it will stop flying in 2019, citing a “security and operational” threat.

The company also said that “a new set of rules will be implemented in the coming weeks, including a reduction in fares for some groups.”

In September, the New York Times reported that the airline was preparing to retire the majority of its Airbus A330neo aircraft, which have long been used by the airline to ferry passengers between Paris and other parts of the country.

The airline said the A330s would no longer be used for the foreseeable future, citing safety concerns, and would not replace them.

The New York-based carrier has not responded to requests for comment.

United Airlines (UAL) said it would suspend flights between Washington, D.C., and San Francisco starting this month.

A UAL spokesperson said in a statement to Business Insider that “we are deeply saddened by the terrible terrorist attack that took place in Paris, but are focused on our immediate priorities and are working closely with our partners in Washington, DC to help us through this difficult time.”

The Boston-based JetBlue Airways said on Tuesday it would cancel all flights to and from the U.K. until November 1, citing “ongoing safety and security concerns.”

The company said in an emailed statement that it is working closely “with our partners and passengers, including the Government of the United Kingdom.”

Airlines have also taken a hard look at the way they run their fleets and plans for the future, including whether they will focus more on connecting passengers or on boosting profits.

The Air France-KLM alliance has faced criticism in the past for its business practices, but the airline has recently begun to diversify its business model to include connecting passengers.

In October, the UAW said it was severing ties with the Delta Air Lines, citing its failure to protect workers in the manufacturing sector.

The United Airlines-Airliners Alliance also said it had reached an agreement with FedEx, but said that the arrangement would expire in 2021.

The Paris attacks left 129 people dead and more than 350 wounded, and led to a dramatic overhaul of how U.C.L.A. operates, as it seeks to address a growing number of terrorism threats.

The UAL-owned airline has now been operating a new “air mobility” model that combines the services of Air France and Delta Air, which now includes flights between London and New York.