UNITED NATIONS, Sept. 24 (Xinhua) -- A thaw in U.S.-Iran relations was met with cautious optimism on Tuesday after the presidents of the two countries sent out olive branches to each other.
U.S. Secretary of State John Kerry is scheduled to meet Iranian Foreign Minister Mohammad Javad Zarif on Thursday, marking the highest-level talks between the two states in decades.
In his address to the annual UN General Assembly session, U.S. President Barack Obama said he had directed Kerry to pursue a new round of talks with Iran on the grounds that Tehran had signaled to chart a "more moderate course" in its nuclear program.
"The roadblocks may prove to be too great, but I firmly believe the diplomatic path must be tested," Obama said.
Making his debut at the UN General Assembly after taking office in August, Iranian President Hassan Rouhani said his country and the United States can arrive at "a framework to manage our differences," noting he "listened carefully" to Obama's speech earlier Tuesday.
However, the ice-breaking moment was overshadowed by failed attempts to arrange an encounter of the two leaders on informal occasions during the UN gathering.
Rouhani skipped a private lunch hosted by UN Secretary-General Ban Ki-moon on Tuesday, which was open to all leaders at the assembly and where he could run into Obama.
U.S. officials confirmed that no Obama-Rouhani meetings will take place this time, saying that the difficulty in arranging such an encounter is on the Iranian side.
Meanwhile, the opportunity of a resumption of talks also came amid warnings and doubts from both countries as well as the international community.
On the eve of Rouhani's UN trip, former Iranian President Mohammad Khatami said it required a degree of courage and optimism from the West to listen to the voices of the Iranian people who have been painfully targeted by unjust sanctions.
In an article published Monday in The Guardian newspaper of Britain, the moderate former president also warned that "failure to create an atmosphere of trust and meaningful dialogue will only boost extremist forces on all sides."
In the United States, Obama was also advised by lawmakers to view the promises of Rouhani with caution.
In a letter to Obama, several senators cast doubt on the intentions of Rouhani. They urged the White House to keep the pressure of sanctions on Iran and stand firm to prevent the country from developing nuclear weapons.
"Iran has not changed course and is close to obtaining this capability that will likely result in a cascade of nuclear proliferation in one of the world's most volatile regions," reads the letter.
Also Tuesday, Israeli Prime Minister Benjamin Netanyahu said his country "will not be fooled by half-measures that merely provide a smokescreen for Iran's continual pursuit of nuclear weapons and the world should not be fooled either."
Swiss Foreign Minister Didier Burkhalter said Iran nuclear talks may resume in Geneva in October. The meeting would be between chief negotiators from Iran and the so-called P5+1 group of the five permanent UN Security Council members -- Britain, China, France, Russia and the United States -- plus Germany.
Among the warnings and doubts, Rouhani, who was once the chief negotiator of the Iranian side, said Tuesday that he believes the ice was already "beginning to break" and the environment was changing amid tensions over nuclear issues.
In an interview with CNN aired Tuesday evening, Rouhani acknowledged that there had been "some talks" to arrange a meeting with Obama to give the two an opportunity to "talk with each other" but there was not sufficient time to really coordinate such a meeting.
"I would like to say to American people: I bring peace and friendship from Iranians to Americans," said Rouhani in English at the end of the interview as the CNN host requested him to deliver a message in English directly to the U.S. public.