Fighters from the Islamist group killed 700 Israelis and abducted dozens in Saturday’s attacks, the deadliest such incursion in decades, prompting Israel to retaliate by pounding the Palestinian enclave of Gaza.

Regulators including the United States’ Federal Aviation Administration, the European Union Aviation Safety Agency and Israel’s aviation authority urged airlines to use caution in the region’s airspace, but stopped short of suspending flights.

Israel’s civil aviation authority asked airlines to “review current security and threat information” amid the conflict, and changed some air traffic routes. It noted that delays were expected and advised airlines to carry extra fuel.

On Sunday, U.S. air carriers United Airlines (UAL.O), Delta Air Lines (DAL.N) and American Airlines (AAL.O) suspended direct flights following the FAA’s caution advisories.

The U.S. airlines normally run direct services from major cities such as New York, Chicago, Washington, DC and Miami.

United said it had run two scheduled flights to the United States from Israel late on Saturday and early on Sunday but then suspended services. Delta representatives said flights this week were cancelled and the situation was being monitored.

Airline Responses

In Europe, Air France (AIRF.PA) and Finland’s Finnair (FIA1S.HE) suspended direct flights.

Britain’s easyJet (EZJ.L) halted flights to Tel Aviv on Sunday and Monday, and said it would adjust the timings of flights over the next few days.

Hungarian budget carrier Wizz Air (WIZZ.L) cancelled flights to and from Tel Aviv until further notice.

“Wizz Air is the most affected group with its operations accounting for some 9.4% of Israel’s total October capacity and … representing some 2.3% of the carrier’s total schedules,” Irish brokerage Goodbody said.

Lufthansa (LHAG.DE) group, also among the airlines most exposed to Israel, according to Goodbody, cancelled flights to and from Tel Aviv through Monday.

Portugal’s TAP suspended flights up until Monday and offered refunds or rescheduling at no additional cost.

Virgin Atlantic said it would continue to run some flights but that customers could rebook or request a refund until Oct. 15.

Some airlines continued to fly to Israel.

Flight tracking site Flightradar24 listed upcoming Ben Gurion arrivals from airlines including Ryanair, flyDubai and national carrier El Al.

Israel’s airports authority said on its website Ben Gurion continued to handle arrivals and departures.

Hainan Airlines (600221.SS), the only Chinese airline to fly between China and Israel, cancelled flights between Tel Aviv and Shanghai on Monday.

It said it would continue flights linking Beijing and the southern tech hub of Shenzhen with Tel Aviv while waiving fees for cancellations before Oct. 20.

Cathay Pacific (0293.HK) cancelled its flight between Hong Kong and Tel Aviv due on Tuesday and said it would provide further updates about the next flight on Thursday.

Korean Air (003490.KS) cancelled its Monday flight between the port city of Incheon and Tel Aviv and warned future flights may be irregular.

The Competition Commission of India (CCI) had been scrutinizing the deal, announced last November, and had flagged concerns that the merged entity could have a monopoly in the domestic market.

The CCI said its initial review showed the market share of the Tata Group could be more than 50% in at least seven domestic markets, raising competition concerns, sources told Reuters last month.

Air India did not immediately respond to a Reuters request for comment.

Air India’s merger with Vistara, a joint venture between Tata and Singapore Airlines, will pose a challenge to local rival and market leader IndiGo (INGL.NS).

The process of inviting an Expression of Interest (EoI) signifies the formal commencement of seeking buyers or investors for a potential investment, in line with procedural requirements under Indian law.

Go Airlines, which operated the Go First carrier, did not immediately respond to a Reuters request for comment.

Go Airlines filed for bankruptcy protection in May blaming “faulty” Pratt & Whitney engines for the grounding of about half its 54 Airbus (AIR.PA) A320neos. The engine maker had said the claims are without merit.

According to regulations, the issuance and publication of the Form G – related to the invitation for EoI – would be the “prescribed next – step for taking the insolvency to its logical conclusion,” said Abhirup Dasgupta, a partner at HSA Advocates,

“The final resolution will, however, be subject to the crystallisation of the rights of the lessors,” Dasgupta, who specialises in insolvency law but is not involved in Go First’s proceedings, said

Willie Walsh, director general of the International Air Transport Association, told Reuters the topic had been raised by “every single one” of the airline CEOs he had met as the industry gathers for a three-day annual meeting in Istanbul.

Airlines “are not concerned about the macroeconomic environment, they’re concerned about the access to spare parts for their existing aircraft and the delivery of new aircraft. So it’s definitely got to hold back capacity growth,” he said.

“It’s frustrating because airlines can see strong demand, but they’re not able to match supply with demand in many markets. And this is something we want to see resolved.”

Airbus (AIR.PA) and Boeing (BA.N) have blamed supply chains for delivery delays, while bottlenecks in a network of engine repair shops have also forced airlines to ground dozens of jets.

The gathering comes two weeks before the Paris Airshow, where supply pressures are likely to overshadow new orders.