U.S. Strikes on Nuclear Sites in Iran

U.S. Strikes on Nuclear Sites in Iran

U.S. Strikes on Nuclear Sites in Iran

June 23, 2025 (IN12571)

On the evening of June 21, 2025, the United States carried out air- and sea-launched strikes on three nuclear facilities in Iran in an operation that U.S. officials have said was "very narrowly tailored" to "destroy or severely degrade Iran's nuclear program" and compel Iran to reach a negotiated settlement with the United States. Initial U.S. assessments suggest the sites were severely damaged. The status of highly enriched uranium that had been located at one of the sites is uncertain. U.S. officials have said "we don't want to achieve regime change" and that the operation "was not and has not been about regime change," though President Donald Trump wrote on June 22 that he would expect such a development if Iran's leaders could not "MAKE IRAN GREAT AGAIN." The strikes come amid ongoing conflict between Iran and Israel, which had launched its own attack against Iran on June 13. Reactions in Congress to the U.S. strikes have varied, with some endorsements and critiques, and proposals to limit U.S. military involvement in hostilities or endorse related U.S. support to Israel.

Iran-Israel Conflict

Since Israel's June 13 attack on Iran, the two countries have been effectively at war, with Israel conducting airstrikes throughout Iran, including against sites and personnel related to Iran's military and its nuclear and ballistic missile programs, and Iran launching ballistic missile and drone attacks against Israel. The fighting has reportedly killed over 400 in Iran (including a number of senior military officials) and two dozen in Israel. Israeli officials reportedly sought direct U.S. involvement in targeting certain Iranian nuclear facilities via capabilities Israel apparently does not have.

The United States initially said it was not involved in the Israeli attack, and was prioritizing the safety of U.S. forces in the region. President Trump subsequently indicated greater U.S. alignment with Israeli operations. On June 17, President Trump called for Iran's "unconditional surrender," wrote that "We now have complete and total control of the skies over Iran," and indicated that Iranian Supreme Leader Ali Khamenei was an "easy target" but that "We are not going to take him out (kill!), at least for now." On June 19, the President said that he would make a decision about "whether or not to go within the next two weeks," noting a "substantial chance of negotiations." Since April 2025, the United States had been engaged in indirect diplomatic negotiations with Iran; after the Israeli attack, Iran canceled a sixth round of talks, scheduled for June 15.

Operation Midnight Hammer

According to Chairman of the Joint Chiefs of Staff General Dan Caine, the U.S. military operation in Iran involved over 125 U.S. aircraft, including seven B-2 Spirit bombers, and the use of approximately 75 precision guided weapons, including 14 GBU-57 Massive Ordnance Penetrators (MOPs), over the course of 25 minutes. The MOPs were deployed against nuclear facilities at Natanz and Fordow; U.S. officials have described the latter site as particularly concerning due to its location deep underground. A U.S. submarine also launched over two dozen Tomahawk cruise missiles at a nuclear facility at Isfahan.

Figure 1. Timeline of Operation Midnight Hammer

Source: U.S. Department of Defense.

In announcing the strikes on June 21, President Trump asserted that "Iran's key nuclear enrichment facilities have been completely and totally obliterated" and that Iran "must make peace," saying, "If peace does not come quickly, we will go after … other targets." In a June 22 media briefing, General Caine said the "initial battle damage assessments indicate that all three sites sustained extremely severe damage and destruction." The Israeli military initially assessed that the Fordow site had, according to one media report, "sustained serious damage from the strike but had not been completely destroyed," amid some reports that Iran may have moved equipment and parts of its uranium stockpile before the U.S. attack.

Experts continue to debate the extent to which military strikes can irreversibly set back Iran's nuclear program, particularly if strikes increase Iranian leaders' motivation to seek to obtain a nuclear weapon. In March 2025, the U.S. intelligence community assessed that Iran "is not building a nuclear weapon" and that Khamenei "has not reauthorized the nuclear weapons program he suspended in 2003," an assessment President Trump rejected in June 2025.

In an emergency meeting of the United Nations Security Council on June 22, UN Secretary-General Antonio Guterres called for an end to fighting and said "diplomacy must prevail." European leaders have urged restraint and de-escalation, while the Chinese and Russian foreign ministries condemned the U.S. strike. Iran's neighbors largely expressed concern about the U.S. strike and the potential for further military escalation.

On June 23, Iran launched missiles at the Al Udeid Air Base in Qatar, where thousands of U.S. personnel have been based, as stated retaliation for the June 21 U.S. airstrikes. President Trump called Iran's response "weak" and thanked "Iran for giving us early notice, which made it possible for no lives to be lost, and nobody to be injured."

Congressional Responses

Prior to the U.S. attack, some in Congress had introduced legislation to remove U.S. Armed Forces from hostilities against Iran (S.J.Res. 59 and H.Con.Res. 38) and to prohibit funding for the use of military force against Iran (S. 2087); others had introduced legislation supporting "Israel's preemptive and proportional strikes against Iran" as serving to "advance the vital United States national security interest in a nuclear free Iran" (H.Res. 521).

In response to the U.S. attack, some Members of Congress praised the President's decision to strike Iran and welcomed the strikes as "very successful"; others called for greater congressional involvement, or criticized the operation as increasing the risks of an "open-ended conflict" and as "unconstitutional."

Going forward, Iran could again attempt to attack U.S. forces deployed in the Middle East region or beyond; it is unclear whether Iran's ability to do so may be constrained by the losses inflicted by Israel on Iran's senior military leadership and missile program. Other Iranian responses could take the form of attempting to disrupt shipping transiting the Strait of Hormuz, the waterway through which approximately 27% of global oil trade and 22% of global natural gas trade passes. Iran could also attempt to engage diplomatically with the United States, though the Iranian foreign minister previously discounted the prospect of talks while Iran is engaged in conflict with Israel. President Trump wrote after Iran's June 23 missile attack that "[p]erhaps Iran can now proceed to Peace and Harmony in the Region, and I will enthusiastically encourage Israel to do the same."