Hassan Rouhani
Hassan RouhaniReuters

Western diplomats have hailed a "significant shift" in Iran's attitude towards its nuclear weapons program, following the highest-level of talks between the United States and Iran in six years.

Iranian Foreign Minister Mohammad Javad Zarif and U.S. Secretary of State John Kerry met along with diplomats from the UN Security Council members from U.S, Russia, Britain, France and China and Germany (known as the P5+1) in a meeting in New York on Thursday.

Iran and the six world powers have held several rounds of talks on Iran’s nuclear program. The last round of talks was held at the start of April in Almaty but failed, as did previous rounds.

This current round of talks led Zarif and Kerry to echo the same sentiments that they held "constructive" talks and that the diplomats made progress on resolving international issues in a manner that respected the rights of the Iranian people.

"I am satisfied with this first step," Zarif said. "Now we have to see whether we can match our positive words with serious deeds so we can move forward." Zarif insisted Iran's nuclear program was "nothing but peaceful" and pledged to prove it to the international community.

But skepticism remains in Israel and the US, with leaders in both countries emphasising their preference for positive actions, as opposed to words, from Tehran.

Secretary of State John Kerry pointed out that Iran will still need to answer many questions about its nuclear program. Kerry said he was pleased that Zarif "put possibilities on the table," but said a lot of work remained to be done.

"One meeting and a change in tone, which was welcome, doesn't answer those questions yet," Kerry stated.

Thursday’s meeting will be followed by the resumption of nuclear talks in Geneva on October 15th. It will be the first round of talks since Iran's new President Hassan Rouhani took office.

The new president has said that Tehran would not give up "one iota" of its nuclear rights, but has also urged the world to seize the opportunity of his election to resolve the nuclear dispute. Rouhani has said that he would like to reach a deal on the nuclear dispute in three to six months.

Skepticism on Iran has been repeatedly expressed by Israeli politicians, who have described Rouhani as a "wolf in sheep’s clothing," intent on continuing to develop Iran’s nuclear program while fooling the world with comments presenting himself as a moderate.

Analysts have noted that, during his tenure as chief nuclear negotiator with the EU, Rouhani exhibited just such a tendency. A 2008 report in by the British Telegraph newspaper revealed how Rouhani even boasted of deceiving EU diplomats over his country's nuclear program.