TEHRAN - Iran has announced that its cooperation with the International Atomic Energy (IAEA) will now take a "new form," signaling a shift in its approach amid ongoing tensions over its nuclear program.

The process of uranium enrichment increases the concentration of U-235, an isotope that can sustain a nuclear chain reaction. Beginning in 2006, the U.N. Security Council called on Iran to suspend all uranium enrichment, but it endorsed the JCPOA on July 20, 2015.

Officials in Israel are acknowledging that some enriched uranium may have survived the powerful U.S. strikes on Iranian nuclear facilities last month.

Israeli Prime Minister Netanyahu meets with President Trump to discuss Iran strikes, Gaza conflict and Abraham Accords amid new era of U.S.-Israel strategic partnership

The Pentagon on Wednesday sharpened its assessment of Iran's nuclear program, declaring that Iran's ability to build a nuclear weapon following the U.S. strike on its nuclear facilities is "closer to two years" away.

President Donald Trump said on Friday that Iran had not agreed to inspections of its nuclear program or to give up enriching uranium.

The appraisal that Iran’s nuclear hopes had been set back 1 to 2 years by U.S. and Israeli bombings was the latest in a shifting series of pronouncements.

Some of the most important considerations for Tehran on the road to a nuclear weapon are political, not technical, and every delay complicates its calculations.

The intelligence community has not finalized its battle damage assessment for the effects of the U.S. military's strikes on three of Iran's nuclear facilities.

<p>News about Iran&#8217;s nuclear program, including commentary and archival articles published in The New York Times.</p>