It comes as no surprise that Iran has again slowed progress toward an agreement limiting its nuclear program to its declared peaceful purposes. Negotiations have been going on and off since 2003, and during that time Iran has moved ever closer to a capacity to produce weapons-grade material.

But the West keeps trying, for obvious reasons. An aggressive, nuclear-armed Iran is a major threat to peace.

Last week Secretary of State John Kerry announced an extension of the talks that were supposed to have concluded on Sunday.

An interim moratorium on Iran's nuclear programs will continue until Nov. 24, and Iran will get access to funds that will ease the strain on its economy from sanctions and the burdens of the war in Syria.

Iran's delaying diplomacy has been aimed at keeping the United Nations at bay.

Negotiations on stopping Iran's illegal uranium enrichment program started in 2003. By 2005 Iran had broken its initial agreement, and a series of back-and-forth initiatives followed, with Iran making steady progress all the time. Formal talks resumed in 2013.

Meanwhile, Iran has also been making progress toward rescuing the Syrian government, which it relies upon to support militias in Lebanon and Gaza hostile to Israel.

The civil war in Syria and Iran's current negotiating strategy on its nuclear program are linked, and aimed at keeping Western powers, including the United States, from becoming more heavily involved in Syria.

It is notable that shortly before the July 20 deadline for a formal agreement, Iran's Supreme Leader, Ayatollah Ali Khamenei, made it clear that Iran and the United Nations were far apart in their demands.

At the heart of the current impasse in negotiations is how many centrifuges Iran should be allowed by international agreement to operate. Iran admits to having 19,000 centrifuges of various efficiencies producing nuclear material.

A year ago, U.S. officials told The New York Times that Iran should be limited to 5,000 centrifuges for research and development. This centrifuge laboratory would have to be operated under international supervision, because even a centrifuge plant of current size could produce enough highly enriched uranium for a nuclear weapon in a few weeks.

According to Ayatollah Khamenei, the U.N. was willing to allow Iran a capacity of about 10,000 centrifuges - less than 6 percent of what Iran wants.

According to expert sources, Iran's desired total would be enough to supply two large civilian nuclear power reactors with annual fuel replacement.

Iran already has one such reactor, supplied by Russia and has announced it wants another. With a uranium enrichment industry that large, Iran could produce an endless supply of weapons-grade material.

The gap between Iran's demands and the international community's position - which many critics already think is too lax - appears far too large to be resolved via negotiations.

So now the tough question for the Obama administration is how much longer Iran can be allowed to benefit from relaxed economic sanctions while playing the West for time.

Because as long as Iran's stall game keeps working, it can keep advancing toward its longtime goal of a nuclear arsenal.