President Hassan Rouhani said on Thursday Iran has right to develop missiles and ordered his defence minister to expand Iran's ballistic missile plan in response to the US threat to impose new sanctions on the ballistic missile test Iran practiced in October.
"As the US government is clearly still pursuing its hostile policies and illegal meddling ... the armed forces need to quickly and significantly increase their missile capability," Rouhani said in a letter to Defence Minister Hossein Dehghan, published on IRNA, the state news agency.
Meanwhile, Iran's Foreign Ministry spokesman Hossein Jaber Ansari condemned the new US sanctions on international corporations and individuals in reply to the Iran's ballistic missile programme.
Jaber Ansari described the US attempt as "arbitrary and illegal."
"As we have declared to the American government ... Iran's missile programme has no connection to the (nuclear) agreement," state television quoted Ansari as saying.
"Iran will resolutely respond to any interfering action by America against its defensive programmes," said Jaber Ansari.
The Wall Street Journal reported that the potential sanctions would hit at least 12 corporations and individuals in Iran, Hong Kong and the United Arab Emirates for their suspected links on developing Iran's ballistic-missile program.
The US officials have said the Treasury Department keeps a right under the nuclear agreement to blacklist Iranians suspected of involvement in the ballistic-missile program.
A UN team of sanctions monitors said on December 15 that an Iranian missile tested in October was capable of delivering a nuclear warhead and violated a UN Security Council resolution.
Supreme Leader Ayatollah Ali Khamenei has said such new penalties would nullify the nuclear accord.
"There may actually be a link between the accusations made by the United States (about the Gulf incident) and the new sanctions," Mohammad Marandi, a Tehran University professor, told state-run PressTV.
"The regime in Washington is trying to reimpose these sanctions by other means."
Iran reached a long-sought nuclear deal with world powers in July of this year. The deal between Iran and six world powers - Britain, China, France, Germany, Russia and the United States - is aimed at monitoring Iran's most sensitive nuclear work for over 12 years in exchange for immediate relief for the country from the economic sanctions, which have long crippled its economy.