In a show of its resolve to crack down further on Iran, the Trump administration on Monday issued sanctions against more than two dozen people and entities involved in Tehran’s nuclear program, missile tests and trade in conventional weapons.

Among the targets of the new U.S. sanctions are the Iranian Defense Ministry and Venezuelan President Nicolás Maduro, whom the Trump administration accuses of collaborating with Iran to flout a U.N. arms embargo.

“Our actions today are a warning that should be heard worldwide,” U.S. Secretary of State Mike Pompeo said at the State Department, flanked by a high-powered array of senior administration officials. “No matter who you are, if you violate the U.N. arms embargo on Iran, you risk sanctions.”

The new measures came a little more than a day after the administration declared the reimposition of international U.N. sanctions that were lifted under the 2015 nuclear deal with Iran. Except for a handful of allies, most nations say the United States has no legal standing to unilaterally put the sanctions back in place because it withdrew from the agreement in 2018.

The sanctions, announced by the Departments of State, Treasury and Commerce, were put in place under an executive order President Trump signed Monday aiming to deter conventional arms trade with Iran. A U.N. embargo on arms transfers expires next month, a deadline that prompted the United States in August to trigger a “snapback” clause in the agreement.

“My administration will never allow Iran to have a nuclear weapon, nor will we allow Iran to endanger the rest of the world with a fresh supply of ballistic missiles and conventional arms,” Trump said in a statement. Iran denies it is seeking to build a nuclear bomb.

In answer to a question, Pompeo rejected the notion that it had been counterproductive to withdraw from the agreement.

“The regime would have even more money to build more centrifuges, to build more capabilities, to build more air defense systems, to prevent us from having the capacity to prevent them from getting a nuclear weapon,” said Pompeo, alongside Defense Secretary Mark T. Esper, Treasury Secretary Steven Mnuchin, Commerce Secretary Wilbur Ross, national security adviser Robert C. O’Brien and Kelly Knight Craft, the U.S. ambassador to the United Nations.

“All of the elements of the terror state would be enhanced had we not done what President Trump directed back in May of 2018,” Pompeo said.

Pompeo once again urged European countries to accept that sanctions are back in place and called on all countries to comply.

“The country that’s isolated today is not the United States, but rather Iran,” he said,

But Craft implicitly acknowledged Washington’s isolation in the United Nations, which holds its annual General Assembly for the 75th time this week.

“As we have in the past, we will stand alone to protect peace and security at all times,” she said, speaking after Pompeo. “We don’t need a cheering section to validate our moral compass.”

By further tightening the “maximum pressure campaign” that has devastated the Iranian economy over the past two years, the Trump administration risks an escalation of tensions just weeks before the U.S. presidential election. Though Iranian President Hassan Rouhani has vowed a “crushing response” to U.S. “bullying,” some experts do not expect Iran to react strongly as it waits to see whether Democratic nominee Joe Biden wins and picks up the nuclear deal Trump abandoned.

Elliott Abrams, the U.S. special envoy for Iran and Venezuela policy, said the administration will continue to expand sanctions until Iran is wiling to pursue a comprehensive negotiation that addresses its “malign behavior.”

“We are always open to diplomacy with Iran,” he added. “But Iran must respond with diplomacy.”

Coincidentally, Iranian Foreign Minister Mohammad Javad Zarif — himself subject to U.S. sanctions — was speaking by video before the Council of Foreign Relations as Pompeo was announcing the new sanctions.

Zarif said his government is “absolutely not” open to renegotiating the terms of the Iran nuclear deal regardless of who wins the election.

“It’s none of our business,” Zarif said. “For us, the behavior of the U.S. government is important. . . . As a foreign government, we cannot bank on something we do not control.”

Trump has said that if he wins reelection, Iran would immediately want to enter negotiations for a new agreement and that a new pact could be reached within weeks.

Biden has indicated that he would return the United States to the original deal, known as the JCPOA, or Joint Comprehensive Plan of Action, as long as Iran abided by its terms, but would also begin negotiations to alter some aspects of the agreement.

But to reenter the accord, Zarif said, the United States must pledge it would not make new demands beyond its scope of the original deal, and provide compensation for the “billions and billions” of dollars in economic losses to Iran because of sanctions imposed by the Trump administration since it withdrew.

“I really don’t believe anything is impossible, but I believe it’s going to take a lot of effort,” he said. “After these very difficult years of President Trump, it is important for the United States to send the right signals to Iran that it is ready to end this . . . policy of pressure.”

Zarif said the sanctions announced by Pompeo on Monday were “nothing new . . . and I don’t think it will have any more significant impact on Iran. The United States has exerted all the pressure it could on Iran. It had hoped these sanctions would bring our population to its knees. It didn’t.”

Since the Trump administration’s withdrawal from the deal and reimposition of U.S. sanctions, Iran has exceeded its limits on the amount of uranium it can enrich. Asked about reports that it now had enough low-enriched uranium to process fissile material to build one nuclear weapon by the end of this year, Zarif repeated his government’s contention that it has no intention of building a bomb.

Iran had significant quantities of low-enriched uranium before the agreement and “we didn’t build a bomb,” he said. “Now we have about 3,000 kilograms,” the amount allowed under the deal, which Zarif said was “enough for three” nuclear weapons.

“So we don’t need to wait until next year,” he said. “But we don’t intend to build a bomb.”

Zarif also suggested that Iran plans to retaliate for the killing of Iranian Gen. Qasem Soleimani in a U.S. drone strike in January.

“President Trump ordered the assassination of a national hero for Iran and the region,” Zarif said, adding, “I’m not in the business of making threats, but the book is not closed.”