Differences remain at Iran nuclear negotiation table
伊朗核谈判仍存在分歧

Now let's take a closer look at some of the issues that have been sticking points in the Iran nuclear talks.

Uranium enrichment is one of the core issue of the talks. According to the International Atomic Energy Agency, or IAEA, low-enriched uranium has a lower than 20% concentration of Uranium 235. Uranium that is enriched to 3 to 5% is used in nuclear power plants. Above 80 percent, is highly enriched uranium. And above 90 percent is weapons-grade highly enriched uranium. Western countries want Iran to cut its uranium enrichment capacity. But Iran insists its nuclear plan is limited to civilian use, and should be enlarged instead. In November of 2013, Iran reached a periodic deal with the six world powers, agreeing to halt uranium enrichment above 5 percent, as a condition for eased sanctions against the country.

How many centrifuges Iran should hold is another question in the talks. Currently, the country has about 10-thousand functioning centrifuges. Iran once claimed that in order to meet its future nuclear power demand, it will need 190-thousand centrifuges over the next eight years. Western countries say they can only accept 4-thousand.

Nuclear inspections are another difficult issue. Western powers want Iran to implement the agreement under the overall supervision of the IAEA. They insist the agency's staff should be permitted into Iran's nuclear bases and facilities for inspection and to question Iranian scientists anywhere and anytime. However, Iran's supreme leader Ayatollah Ali Khamenei has strongly rejected this request.

When to cancel the timetable of sanctions against Iran is also a sticking point for negotiators. Iran wants Western powers to get rid of all sanctions as soon as a comprehensive deal is reached. While Western powers say they will do this step by step, and the whole process could last one or two decades.