Airlines may be reluctant to receive aircraft because of the ongoing uncertainty of US tariffs and their impact on aircraft costs, said Willie Walsh, Director General of the International Air Transport Association (IATA).Walsh stressed that tariffs will pose substantial issues not only for Boeing (BA.US) and Airbus but also for most airlines.(Real-time Streaming US Stocks Quote; Except All OTC quotes are at least 15 minutes delayed.)Related NewsUBS: CN Aviation Sector May Face Ticket Price Downside Risks in 2H; Ratings Reiterated as Sell for AIR CHINA, CHINA EAST AIR