President Donald Trump has issued a stark warning to Iran, urging the country to accept a nuclear deal to avoid further “planned attacks,” citing that “there has already been great death and destruction, but there is still time to make this slaughter… come to an end.”

Here is a timeline tracing key developments in Iran’s nuclear programme over the years. The United States and Iran, then ruled by Shah Mohammad Reza Pahlavi, who was brought to power by a 1953 CIA coup against the country's democratically-elected Prime Minister Mohammad Mosaddegh, sign an agreement on civil nuclear cooperation.

US and Iranian officials are scheduled to hold a sixth round of talks on Tehran's escalating uranium enrichment programme.

For much of the 20th century, the US and Iran maintained friendly relations. During the Cold War, Washington depended on the Shah of Iran to counter Soviet influence in the oil-rich Middle East.

U.S. President Donald Trump appeared to shift his previously optimistic tone on the talks this week, saying he was

The United States has pulled some diplomatic staff and military families out of the Middle East, citing unspecified regional security risks. Read more at straitstimes.com. Read more at straitstimes.com.

This is called the safeguards obligation and is part of the Non-Proliferation Treaty. Iran is legally bound to declare all nuclear materials and activities and allow IAEA inspectors to verify that none have been diverted for non-peaceful uses.

The sixth round of Iran-US nuclear talks is planned for Sunday, Tehran said as the two sides appear locked in a standoff over uranium enrichment nearly two months into the high-stakes negotiations.