The U.S. military has characterized Monday’s strikes in southern Iran as defensive, saying targets included missile launch sites and boats placing mines, and said the U.S. acted with “restraint” in light of the weekslong ceasefire.

Iran’s foreign ministry called the strikes a ceasefire violation and warned that Washington would bear responsibility for “all consequences,” without details.

“The Islamic Republic of Iran will leave no act of aggression unanswered,” it added in a statement.

Iran’s Revolutionary Guard on Tuesday said it had shot down and deterred drones and a fighter jet that entered its airspace, according to Iran’s official Mizan news agency, which did not specify when the incident occurred.

It wasn’t immediately clear what the developments would mean for negotiations. The strikes came after Iranian parliament speaker Mohammad Bagher Qalibaf went to Qatar as part of the talks, which U.S. President Donald Trump said Monday were “proceeding nicely.”

The strikes were the latest flare-up in the fragile ceasefire that began April 7 and has largely held.

Negotiations center in part on the Strait of Hormuz, the crucial waterway off southern Iran through which a fifth of the world’s crude oil and natural gas passed before the war began with U.S.-Israeli strikes in February. Tehran retaliated by effectively closing the strait, stranding hundreds of ships and shocking the global economy.

The U.K. Maritime Trade Operations Center said an explosion was reported Tuesday morning aboard a tanker in the Gulf of Oman, which lies near the strait. No one was injured in the blast; there was no immediate information on the cause.

Besides disrupting energy markets, the strait’s closure is also squeezing fertilizer supplies worldwide. The full impact might not become clear until harvests that are months away. U.N. Food and Agriculture Organization Director-General Qu Dongyu, warned at an event in Rome Tuesday that “the decisions we make now will determine whether this remains a manageable shock or evolves into a deeper global food security crisis in 2026 and 2027 and beyond.”

The strait has become a powerful lever for Tehran in talks, joining the long-running issue of Iran’s nuclear program and highly enriched uranium. Iran, in turn, wants the U.S. to lift its military blockade of Iranian ports that began on April 17.

“What we are witnessing today is not only a geopolitical crisis, it is a systemic shock to the global agrifood system,” Qu said Tuesday.

Trump has introduced a new angle in negotiations for a deal on the war, saying any agreement to end the war should include a requirement for several additional countries, including Saudi Arabia and Pakistan, to join the Abraham Accords, a series of U.S.-brokered diplomatic, economic and security agreements aimed at normalizing relations with Israel.

Bahrain and the United Arab Emirates became the first countries to join in 2020; Sudan, Morocco and Kazakhstan have followed. Egypt and Jordan already formally recognize Israel and have long-standing peace treaties. Turkey first recognized Israel in 1949.

Israel’s conduct against Palestinians, including in the war against Hamas in the Gaza Strip, has alienated Gulf Arab states and the wider Muslim world, but Trump has been keen to build on the Abraham Accords, forged during his first term. He has even suggested that Iran eventually could sign on.