The could seize IP space using a security system, which began deployment three years ago, called the RPKI[1].

If you use the RPKI to protect the internet against BGP attacks, you provide a technical mechanism which governments, or other actors, could use to seize addresses. I just presented a paper on this[2].

IP takedowns are a risk, the Iranian case is not the only example, for instance RIPE was ordered to seize IP Space by a dutch court[3].

[1]: http://en.wikipedia.org/wiki/Resource_Public_Key_Infrastruct...

[2]: See paper "From the Consent of the Routed" http://www.cs.bu.edu/~goldbe/papers/RPKImanip.html

[3]: http://www.internetgovernance.org/2013/08/09/court-says-ripe...