As world powers are stepping up efforts to return to a nuclear deal with Iran, the Islamic Republic is testing nuclear-capable ballistic missiles in violation of the agreement, Israel revealed this week.

According to a report by Israel Hayom Friday, Israeli Ambassador to the United States and the United Nations Gilad Erdan has sent a letter to the UN Security Council and UN Secretary-General Antonio Guterres, revealing information about Iran’s illegal missile activities, which violate Resolution 2231 that endorsed the Joint Comprehensive Plan of Action back in 2015.

Iran’s Revolutionary Guards Corps has been testing missiles for several months, including nuclear ones, Erdan wrote in his letter. He called on UNSC members to condemn Tehran’s actions.

The Security Council must respond to Iran’s threats to world peace and security, Erdan wrote, and described in detail the kinds of missiles the regime was testing and what their capabilities were.

During one of its military exercises in mid-January, called “The Great Prophet 15,” Iranian forces tested missiles of various ranges, including the Sejjil and Qader ballistic missiles, which are capable of carrying a 650 kg (1400 pounds) warhead and have a range of approximately 2,000 km (1,200 miles).

Tehran’s technological progress once again reflects the link between the regime’s space and military programs, which work together to develop the regime’s nuclear capabilities, Erdan wrote in his letter.

Meanwhile, Iran warned Israel and the US Thursday about possible retaliation after the Jewish state struck Saviz, an Iranian-flagged ship, in the Red Sea on Tuesday.

“No doubt the United States was involved,” an Iranian military spokesman said.