They've already been doing this relatively covertly, this is just an overt extension of that policy. Note that this gives the US President the authority to launch cyber attacks against American targets as well:
Obama orders US to draw up overseas target list for cyber-attacks
Exclusive: Top-secret directive steps up offensive cyber capabilities to 'advance US objectives around the world'
Barack Obama has ordered his senior national security and intelligence officials to draw up a list of potential overseas targets for US cyber-attacks, a top secret presidential directive obtained by the Guardian reveals.
The 18-page Presidential Policy Directive 20, issued in October last year but never published, states that what it calls Offensive Cyber Effects Operations (OCEO) "can offer unique and unconventional capabilities to advance US national objectives around the world with little or no warning to the adversary or target and with potential effects ranging from subtle to severely damaging".
It says the government will "identify potential targets of national importance where OCEO can offer a favorable balance of effectiveness and risk as compared with other instruments of national power".
The directive also contemplates the possible use of cyber actions inside the US, though it specifies that no such domestic operations can be conducted without the prior order of the president, except in cases of emergency.
Full article is here:
www.guardian.co.uk/world/2013/jun/07/oba...rgets-cyber-overseas 
