US State Department Spokesman Matthew Miller said the US remains "seriously concerned about Iran’s continued expansion of its nuclear program in ways that have no credible civilian purpose".

During his Monday briefing, he said Iran's continued production of highly enriched uranium remains a major policy concern. The statements came as two confidential reports from the UN's nuclear watchdog were distributed to member states on Monday, providing a grim assessment of Iran's nuclear program.

Persistent obstacles to thorough inspection procedures continue to obscure the true nature of Iran's activities, heightening concerns about the intentions of the Tehran regime.

IAEA head Rafael Grossi said that "public statements made in Iran regarding its technical capabilities to produce nuclear weapons" have only increased "concerns about the correctness and completeness of Iran's safeguards declarations".

Iran's enriched uranium stockpile has now exceeded 5.5 tons, representing an increase of one ton since October. Within the stockpile are 712.2 kilograms of uranium enriched up to 20 percent and 121.5 kilograms enriched up to 60 percent. Notably, the latter category has seen a decrease of approximately 7 kilograms over the past hundred days.

The Wall Street Journal reported that Iran has decided to reduce its stockpile of 60 percent enriched uranium over the last three and a half months "by deliberately diluting the material by mixing it with low-grade 2 percent material", noting that it is the first time the International Atomic Energy Agency has reported a quarterly drop in Tehran's highly enriched stockpile since Iran started production.

According to definitions established by the International Atomic Energy Agency (IAEA), Iran would require a minimum of 42 kilograms of uranium enriched to 60 percent to produce a nuclear bomb.

Iranian authorities have consistently asserted that Iran's nuclear program is solely intended for peaceful purposes. However, nuclear experts overwhelmingly argue that the levels and quantities of enrichment undertaken by Iran since 2021 cannot be justified in the absence of a weapons program.