By Anne Kauranen, Tim Hepher and Rajesh Kumar Singh HELSINKI/PARIS/CHICAGO (Reuters) -Airlines are bracing for potentially lengthy blockages of key east-west flight corridors after the European Union and Moscow issued tit-for-tat airspace bans and Washington did not rule out similar action in response to Russia’s invasion of Ukraine. Industry officials expect the Biden administration would ban Russia from U.S. airspace. The White House said on Monday while barring Russian flights was not off the table, it had yet to make a decision. “There are a lot of flights that U.S. airlines fly over Russi…