Microsoft email server hacks put Biden in a bind
The scale of a hack on Microsoft Exchange is beginning to emerge, with tens of thousands of organisations potentially compromised.
The attack used previously unknown flaws in the email software - and sometimes stolen passwords - to steal data from targets' networks.
Microsoft says the attackers are "state-sponsored and operating out of China".
And while it initially thought the number of attacks had been "limited", it has since reported "increased use" of the tactics - probably because other hackers are piling in to take advantage of the now public vulnerabilities before systems are patched