Iran’s nuclear game is in the final quarter, they’re ahead and they’re playing out the clock. If they can string us along with diplomacy for a few more months, and forestall sanctions, they’ll be the first Muslim country in the Middle East with nuclear weapons.

At this point, is there any way to stop Iran short of bombing? Maybe. 

Sanctions, with Russian and Chinese cooperation, might be enough to convince the Mullahs to drop their nuclear weapons program, or encourage the growing dissident movement to force a change of government. 

It’s a Hail Mary pass, but we should give it a try – because the only remaining options – bombing Iran or letting Iran get the bomb – would be catastrophic. But the sanctions must be crippling, designed to bring Iran’s economy to an immediate and screeching halt, and they must be imposed now. 

If we wait to start sanctions at some vague point in the future AFTER we’ve exhausted diplomacy – the Iranians will make sure negotiations don’t fail but they’ll make sure negotiations don’t succeed either.-- They, like the North Koreans, will keep the West's hope of diplomacy alive right up to the point when they declare BINGO we’ve got the bomb!

Getting Russia and China to cooperate won’t be easy, of course. Russia sells Iran military equipment and China buys their oil, and neither feel directly threatened by a nuclear Iran.

Russia might have been more willing to help out, had we held out the missile shield as a quid pro quo. But President Obama cancelled it recently, hoping that his goodwill gesture would encourage Russia to ‘reset’ relations with us.--Instead it’s got them laughing behind our backs. We’ve thrown away our best bargaining chip and gotten nothing in return.

Now the Russians see very little between them and their dream world-- high oil prices and no competition – which is exactly what will happen if Israel concludes it has no choice but to attack Iran. A military conflict would also likely turn into a larger regional conflict as Iran retaliates by mining the Strait of Hormuz-- the chokepoint for Arab oil-- and unleashes Hezbollah and Hamas on Israel and awakens sleeper cells around the world.

But the United States and hopefully Germany, France and the United Kingdom, should move ahead with banking and financial sanctions even if we have to do it alone. We can give companies a choice-- do business with Iran or with us-- but not both.

President Obama has put great store in diplomacy and his personal ability to get negotiations going. But diplomacy without leverage isn’t negotiating, it’s begging. And with Iran standing at the threshold of nuclear weapons, begging is NOT the right strategy.

Kathleen Troia "K.T." McFarland served in national security posts in the Nixon, Ford and Reagan administrations. She is frequent contributor to the FOX Forum and Foxnews.com's "Strategy Room." She also appears weekly in the Foxnews.com video blog "DefCon3."