If the Iranian facility would be completed, it would be a nightmare scenario for the US — and Israel — that would send US-Iranian relations into a new escalatory spiral. If Iran managed to acquire a nuclear weapon, it would cross several US and Israeli red lines. Diplomacy is the best way to prevent conflict. However, the White House has said that the president has not removed any option from the table.
The only party to blame for increasing tensions between the US and Iran is Washington. Iran agreed to maintain a nuclear program only for civilian uses, but the US and Israel — both of which possess nuclear weapons — sought to inflame tensions. Iran wants peace and ultimately has no interest in arming itself with nuclear weapons, but Washington is forcing its hand.
There's a 75% chance that Iran will possess a nuclear weapon before 2041, according to the Metaculus prediction community.