Iran will speed up enrichment of uranium and pull further out of the nuclear deal with world powers, Iranian officials said, in a move that could bring additional retaliatory measures by the United States in the form of sanctions or even military strikes.

Behrouz Kamalvandi, the spokesman for Iran's Atomic Energy Organization, said Wednesday that Iran's move follows a two-month ultimatum given to European signatories to the deal to help Iran navigate U.S. sanctions that have harmed its economy. Kamalvandi's remarks were carried by the state-run IRIB news agency.

Separately, Ali Shamkhani, secretary of Iran's Supreme National Security Council, said Iran "will forcefully take the second step of reducing its commitments" to the nuclear deal on July 7 so "Iran's 'patience'" is not confused with "weakness." Shamkhani's comments were reported by the state-run Fars News Agency.

In early May, Tehran suspended limits on its production of enriched uranium and heavy water, moves that did not technically violate the deal but aggressively signaled that its patience with an accord that the U.S. has already pulled out of was wearing thin.

France, Germany and the United Kingdom, who stayed in the deal, have not been able to ensure that Iran retains access to international oil markets and banking services.

Since then, tensions between Iran and the U.S. have risen markedly amid the shooting down of an American drone by Tehran, sabotaged oil tankers in the Persian Gulf and the Pentagon's dispatch of troops and B-52 bombers to the Middle East.

"Any attack by Iran on anything American will be met with great and overwhelming force. In some areas, overwhelming will mean obliteration," Trump wrote on Twitter on Tuesday, less than a week after he called off a planned U.S. missile strike on Iran in retaliation for the shooting down of the U.S. drone. In recent days, the president has oscillated between tough talk and conciliatory rhetoric over what he may do next.

"I hope we don’t (go to war) but we’re in a very strong position ... It wouldn’t last very long ... I’m not talking boots on the ground ... I’ve been very nice to them ... They shot down our drone ... I like Iranians very much," Trump said, appearing on Fox Business on Wednesday.

Trump claimed before he took office, Iran was going to "take over" the Middle East, an assertion that may relate to Tehran's support for militant groups in Lebanon, Syria and Yemen.

"I don’t think (Iran's) leadership is smart ... Iran’s going down the tubes," he said on Fox, in response to Iranian President Hassan Rouhani's remarks that the White House is "suffering from mental disability" with "no sane person" in charge.

Under terms of the nuclear deal negotiated in 2015 under the administration of then-President Barack Obama, Iran agreed to have less than 300 kilograms (661 pounds) of uranium enriched to a maximum of 3.67%. Iran has stuck to those terms, according to repeated verifications by the United Nation's nuclear watchdog. Before the deal, Iran enriched uranium as high as 20%, close to weapons-grade levels.

"The deadline of the Atomic Energy Organization for passing the production of enriched uranium from the 300 kilogram border will end tomorrow," Kamalvandi said.

Iran has long insisted that its nuclear program is intended for peaceful, civilian purposes only, although that has been met with skepticism in world capitals.