A global landmark agreement on the Iranian nuclear program is expected on Tuesday morning, marking the culmination of 12 years of on-off diplomacy, and potentially the beginning of a new era in relations between Iran and the West, the Guardian reports.

An announcement on the agreement would come on the 18th day of almost uninterrupted negotiations in Vienna, involving foreign ministers from seven countries and the EU’s foreign policy chief, Federica Mogherini.

The ministers – from Iran, the U.S., UK, Russia, China, France and Germany – are expected to issue a statement and appear for a photo mid-morning, followed some time later by a press conference, according to the Guardian.

At some point President Obama and his Iranian counterpart, Hassan Rouhani, will make statements from their capitals.

It is not clear how much of the estimated 100 pages of text, including five annexes, will be published on Tuesday. Much of the outline of the agreement is already known, having been provisionally settled in Lausanne in April, the Guardian says.

It involves Iran accepting curbs on its nuclear program in return for sanctions relief, but many of the critical, politically-charged details will only be made public on Tuesday.

In particular, it will become clear whether the arms embargo and missile program restrictions on Iran will remain in place and at what point the agreement will be codified as a UN security council resolution.

On Monday, the Iranian president’s office was forced to delete a premature tweet in his name that appeared to welcome a nuclear agreement which had yet to materialize.

The deleted tweet on the English-language account under president Hassan Rouhani’s name declared: “#IranDeal is the victory of diplomacy & mutual respect over the outdated paradigm of exclusion & coercion. And this is a good beginning.”

Soon after, a new tweet was posted in its place, adding the word ‘if’ at the beginning.