Bank hacks in Vietnam and Bangladesh have sparked concerns within global banks, some of which are privately pressing the Swift interbank network to shore up security at its 11,000 members.

A key figure is missing in the court documents outlining the biggest computer attack ever of the U.S. financial system: the actual hacker.

Russian computer attacks have become more brazen and more destructive as the country grows increasingly at odds with the U.S. and European nations over military goals first in Ukraine and now Syria.

Sabre confirmed that its systems were breached recently, while American Airlines said it is investigating whether hackers had entered its computers.

The previously unreported breach adds airlines to a growing list of strategic U.S. industries and institutions that have been compromised.

Some investigators suspect the attacks were part of a sweeping campaign to create a database on Americans that could be used to obtain commercial and government secrets.

Concern is data could be used to target workers with sensitive information who could be subjects of traditional blackmail tools.

Investigators of Anthem Inc.s data breach are pursuing evidence that points to Chinese state-sponsored hackers who are stealing personal information from health-care companies for purposes other than pure profit.