Iran's foreign minister mocked US President Donald Trump's claim Tehran was "not living up to the spirit" of the nuclear deal on Friday, saying Washington was flouting the accord.
"We'll see if US prepared to live up to letter of #JCPOA (nuclear deal) let alone spirit," Foreign Minister Mohammad Javad Zarif tweeted.
"So far, it has defied both. Should I use my highlighter again?"
Zarif is almost as avid a user of Twitter as Trump despite it being officially banned in Iran.
A day earlier, he hit back at US claims that the 2015 deal with world powers was a failure by highlighting certain sections and sharing them on Twitter.
He pointed to sections that require US government officials to "make every effort to support the successful implementation of this JCPOA including in their public statements" and to refrain from any policy intended to "adversely affect the normalisation of trade and economic relations with Iran".
Iran says the US continues to frustrate its efforts to rebuild trade ties with the rest of the world through remaining sanctions, and denies any desire to build a nuclear bomb.
Trump has regularly criticised his predecessor for signing the deal, which he described on Thursday as "a bad one, as bad as I've ever seen negotiated".
He has ordered a 90-day review of whether to abandon it -- a move that would be strongly opposed by the other signatories to the deal: Britain, China, France, Germany and Russia.
The US admitted this week that Iran has stuck to its side of the bargain, but Secretary of State Rex Tillerson said it would not stop Iran becoming a nuclear-armed state, and Washington officials regularly accuse Iran of fomenting unrest in the Middle East and sponsoring terrorism.
© 2017 AFP