He and his team also traveled to Berlin this week to meet counterparts from Europe, "to see if we can secure a supplemental agreement addressing the deficiencies of the Iran nuclear deal", he said in Vienna.
"Unilaterally rolling back or killing the Iran deal, directly or indirectly, would tell the North Koreans in the most explicit way that the promises of the U.S.do not mean anything", Yun added.
Changes are expected by May 12 - the next deadline for Trump to waive sanctions against Iran and the date he has set for United States allies to make changes to the Joint Commission Plan of Action, as the Iran deal is formally known, to address what he sees as its flaws.
Still, the issue is highly sensitive because the 2015 pact between Iran and six major powers ― Britain, China, France, Germany, Russia and the United States ― lifted worldwide sanctions that crippled Iran's oil-based economy.
The UN's nuclear energy agency, the IAEA, confirmed in February that Tehran had met its obligations under the agreement.
In exchange for Iran curbing its nuclear program, global nuclear-related sanctions that had been slapped on Iran had been lifted, starting in 2016 under the terms of the JCPOA, as well as granting Iran access to frozen capital.
Corker said that while the Europeans wanted to keep the deal in place, they were having problems reaching a common position on the so-called sunset provisions, vehemently opposed by Trump, which will expire in eight to 13 years, freeing Iran from numerous pact's provisions.
"When you look at the Iran deal, I think it's awful".
"The (deal) can perhaps delay Iran's nuclear weapons program for a few years", he wrote at the time.
Rex Tillerson, who was sacked Tuesday as secretary of state, always concluded that Iran was complying as global monitors have reported, although not in its "spirit". Pompeo "is certain to advise the president to withdraw the United States from our obligations under the nuclear agreement", said Diplomacy Works, a group of mainly former Obama administration officials that lobbies for staying in the deal. Iran repeatedly refused to discuss its missile program with the Western powers, adding that its missile program was being developed exclusively for defensive purposes.
Joint Comprehensive Plan of Action (JCPOA) entered yesterday an intensive care unit amid talks in Vienna and Berlin, a planned European Union move, and expected high-level consultations in the upcoming two months, before US President Donald Trump announces his final decision on the nuclear deal.
"This is the third meeting that we have had with the E3, (we) had very good discussions. So we were not really thinking the same", he was quoted as saying the magazine. These beliefs dovetail nicely with Trump's views about heaping "maximum pressure" on Pyongyang and that the Iran deal should be radically altered or scrapped.
In January, Trump said the deal, which he has called "disastrous", had to be "fixed" by May 12, when it next comes up for review, or the United States would walk away from it. Mr. Trump's White House has blamed Corker for the Iran deal in the past.