In May, Iranian President Hassan Rouhani warned the country would enrich its uranium stockpile closer to weapons-grade levels in 60 days if world powers fail to negotiate new terms for the nuclear deal.
Acting U.S. Defense Secretary Patrick Shanahan announced on Monday the deployment of about 1,000 more troops to the Middle East for what he said were "defensive purposes", citing concerns about a threat from Iran.
Israeli Prime Minister Benjamin Netanyahu said the worldwide community should reinstate sanctions if Iran follows through on its threats, adding: "In any case, Israel will not allow Iran to obtain nuclear weapons".
Iran attempted to shoot down a USA drone that was surveilling the attack on one of two tankers hit in the Gulf of Oman last week, CENTCOM said.
Iran's Armed Forces Chief of Staff, Major General Mohammad Baqeri, denied on Monday that Iran was behind the attacks on the tankers. Since then, the USA has sent an additional 1,500 troops and increased defensive capabilities to continue to help deter Iran.
Meanwhile, the Kremlin said Monday that Iran had so far faithfully stuck to the curbs on uranium enrichment agreed as part of the deal, and that Moscow was unaware of any statement suggesting that Tehran meant to stop doing so.
German Foreign Minister Heiko Maas said that US and British intelligence needs to be compared with other information from allies.
Trump flaunts 'secret' migration deal already revealed by Mexico
They continue to say that everything that was agreed between the USA and Mexico is on the table, is out there in public. Mr Trump had agreed to a 45-day time-frame to prove Mexico has been effective in controlling illegal immigration .
Kamalvandi made the announcement during a press conference with local journalists at Iran's Arak heavy water facility that was carried live on Iranian state television. Weapons-grade uranium needs to be enriched to around 90 percent.
The deal required Iran to curb its uranium enrichment capacity to head off any pathway to developing a nuclear bomb, in return for the removal of most global sanctions.
He said: "No other state or non-state actor could plausibly have been responsible".
U.S. Central Command, which oversees American operations in the region, has released a string of materials in recent days demonstrating what it says is Iran's involvement in the attacks. The Arkansas Republican, a veteran of the wars in Iraq and Afghanistan, attempted to undermine the Obama administration's efforts to broker the 2015 deal by publishing an open letter to Iran threatening congressional opposition to the agreement, angering many critics.
Trump appeared to say the deal should not be violated in a tweet that said "Iran to defy Uranium Stockpile Limits".
Following the U.S. withdrawal, Iran and the remaining parties launched talks to save the accord.
He said Tehran had quadrupled the rate of enrichment "and even increased it more recently", meaning that in 10 days it will bypass the limit set out in the accord, which aimed at heading off any pathway to developing a nuclear bomb, in return for the removal of most worldwide sanctions.
Speaking on "Fox News Sunday", U.S. Secretary of State Mike Pompeo reiterated the U.S. official position.