Iran “appears to be in the final stages of modifying” a site where it is suspected the regime conducted tests relevant to the development of nuclear warheads, according to new photos and analysis published by the U.S.-based Institute for Science and International Security (ISIS).

Recent commercial satellite imagery shows new paving and the extent of alternations undertaken at the Parchin site since February 2012. DigitalGlobe imagery from August 13, 2013 shows that the majority of the area at the site has now been asphalted.

Iranian scientists are suspected of using the Parchin facility to test explosive triggers. Tehran has rejected efforts by Western diplomats to secure access to Parchin, and has instead engaged in a systematic campaign to asphalt the area and remove soil samples. The effect, according to IAEA chief Yukiya Amano, is that “it may no longer be possible to find anything even if we have access to the site.” The Associated Press also quotes the previous head of the IAEA’s Iran probe on the possibility of inspection:

Olli Heinonen, also said the standoff meant any inspection by agency experts could be inconclusive even if they do get access. That, he said, meant that Tehran “has lost an important opportunity” to prove that it had nothing to hide.

Their evaluations align uneasily with the claims of some proponents of engaging Iran, who suggest that Tehran could make a major concession by opening up Parchin.

[Photo: Galileo gallery / Flickr]