Tomorrow, the United States will resume nuclear negotiations with Iran for the first time since Tehran lost most of its proxy forces — including thousands of fighters for Hamas and Hezbollah — and its bet that Donald Trump would not return to the Oval Office. No country has worked harder on a nuclear bomb without actually building one than the Islamic Republic. Nor has any country insisted more loudly that it wouldn’t build a weapon.

Now, despite years of technical setbacks, assassinated scientists and sabotaged nuclear facilities, Iran is almost capable of pulling it off — if it makes the political decision to do so, Western intelligence agencies say. It could produce bomb-grade fuel in weeks and a workable weapon in months to a year or so. Israel is once again threatening military action, and the United States has moved B-2 stealth bombers in range.

Trump insists military action won’t be necessary if Iran makes a deal — but it has to move fast at the point of a gun. So talks begin tomorrow in Oman between Trump’s personal negotiator, Steve Witkoff, and Iran’s foreign minister.

I’ve covered the Iranian nuclear program for more than two decades. Today, I’ll explain what changed in recent years and examine the chances that diplomacy might work.

Washington’s view

After Iran watched the United States oust regimes in Iraq and Afghanistan, it stopped developing a nuclear warhead, U.S. intelligence concluded. But Tehran kept options open. It got better at enriching uranium even as it insisted the work was for power plants, medical isotopes and research.

Iran had that right under the Nuclear Nonproliferation Treaty. But the past five presidents feared it would be too easy for the theocracy — one that still reaches for chants like “Death to America” and threatens to obliterate Israel — to fabricate a bomb.