The letter is an indication that the U.S. is "disintegrating” from within, Ayatollah Seyyed Ali Khamenei told members of the Assembly of Experts on Thursday.
According to international regulations, all the countries in the world honor their commitments after change of their governments, the Leader noted.
The Leader went on to say that if an agreement is reached, Iranian officials will know how to act to prevent the U.S. government from violating it.
"Some think that the U.S. with its political, economic and military power needs no trickery and mischief, but in spite of this assumption the Americans need trick and deception and are acting in this way now and this reality makes us concerned,” the Leader stated.
The U.S. always adopts a "tougher and harsher” tone when a deadline approaches for a nuclear deal, he said, adding that the Iranian officials should be careful about this "trick”.
Elsewhere in his remarks, the Leader backed the members of the Iranian nuclear team which are selected by President Hassan Rouhani, saying they are "good and caring people, who work for the country”.
However, the Leader said that he is worried because the other side stabs in the back. "I am worried because the other side is a sneaky and crafty one who stabs with a dagger in your back.”
Elsewhere in his remarks, he stated that understanding of pure Islam is Iran’s main objective.
He also highlighted the importance of presenting pure Islam in countering Islamophobia.
Leader calls Netanyahu ‘Zionist clown’
Ayatollah Khamenei also described Israeli Prime Minister Benjamin Netanyahu, who delivered a speech to U.S. Congress on March 3, as a "Zionist clown”. The Leader said his speech has led to division in the U.S.
"Some American officials, who did not want to side with him, made some remarks,” the Leader noted.