Iranian President Hassan Rouhani on Thursday accused the United States of failing to uphold its end of the historic nuclear agreement by delaying licenses for legitimate transactions and warning banks they could still run afoul of U.S. sanctions.

In a lengthy news conference with reporters in New York, Rouhani allowed that the U.S. government has granted Airbus and Boeing permission to sell aircraft to Iran, a transaction announced Wednesday. But he said it should have been granted eight months ago, when the nuclear deal lifting sanctions for curbs on Iran’s nuclear program was implemented. He called the delay “severe,” and said the U.S. Treasury Department had reminded banks that U.S. sanctions remain in place for missiles and human rights violations.

“They frighten the big banks with the threat of potential action,” he said.

Large international banks with lots of exposure in the United States have acknowledged being concerned about violating U.S. sanctions and incurring huge fines. But they also have said they are reluctant to invest in Iran in large part because of a culture of corruption with virtually no transparency as required in modern day banking.

Along with Russia, Iran is the biggest backer of Syrian President Bashar al-Assad as well as a member of a multinational group trying to stem the violence and negotiate an end to the war. But Rouhani said he could not back a proposal by U.S. Secretary of State John F. Kerry to ground Russian and Syan warplanes so humanitarian supplies could be safely delivered.

“It has nothing to do with grounding flights,” he said, speaking through an interpreter. “If you ground flights, all you do aid the terrorists. They have mortar rounds, tanks, missile systems and artillery. The only thing they lack is an air force.

“Grounding flights is a step against the righteous and for the terrorists.”

Earlier in the day, Rouhani addressed the United Nations in which he criticized what he portrayed as a deliberate attempt by Washington to block Iranian access to the international banking system.

Rouhani cited as one example an April Supreme Court ruling that Iran’s central bank must pay almost $2 billion to victims of terrorist attacks linked to Iran. The court held that Congress acted within its authority in passing a law enabling families of Americans killed in those attacks to recover damages awarded them in several lawsuits. Among them were relatives of those who died in the Marine Corps barracks bombing in Beirut in 1983.

Rouhani started his speech with a mention of the terrorist attack on New York City that happened 15 years ago this month.

“On that day, no one imagined that this occurrence would lead to larger disasters, resulting in a devastating war in the Middle East and the spread of insecurity across the globe,” he said. “This war has sown the seeds of borderless terrorism everywhere on earth.”

Rouhani also slammed neighboring Saudi Arabia, its regional rival that has been engaged in a war of words with Iran over numerous issues: the wars in Syria and Yemen and the death of many Iranians who were among at least 750 people who died on pilgrimage to Mecca during a stampede last year.

“If the Saudi government is serious about its vision for development and regional security, it must cease and desist from divisive policies, spread of hate ideology and trampling upon the rights of neighbors, accept its responsibility for the protection of the lives and dignity of pilgrims and construct its relations with the nations in the region on the basis of mutual respect and accountability” Rouhani said.