VIENNA (Reuters) – Iran says it has begun work to enrich uranium to a higher level, adding to concerns that it wants to stockpile potential material for nuclear weapons.

The following looks at the dangers of Iran’s move:

WHAT ARE IRAN’S MOTIVES?

Iran said it had acted in frustration at the collapse of a U.N.-brokered plan for big powers to provide it with fuel rods made from low-enriched uranium for a medical reactor.

VIENNA/WASHINGTON (Reuters) – Iran has notified the U.N. nuclear watchdog it rejects key parts of a draft deal to send abroad most of its enriched uranium, designed to ease fears the material could be used to make nuclear weapons, diplomats said on Tuesday.

It was Iran’s first apparently formal answer to the proposal hatched in October and echoed months of dismissive or ambiguous remarks made through the media. The United States rejected Tehran’s reply as “inadequate.”

LONDON (Reuters) – A leaked memo appearing to show Iran trying to design an atomic bomb trigger would undercut its assertion that it seeks only peaceful nuclear energy and harden fears it is nearing the capability to make nuclear weapons.

But caveats are in order. The memo in the hands of Western intelligence services and the U.N. nuclear watchdog has not been authenticated. Even if genuine, it may prove no more than a bid to develop competency for a possible nuclear “breakout” in the future, not an outright, illicit program to build bombs.

LONDON (Reuters) – Intelligence suggests Iran worked on testing a key atomic bomb component as recently as 2007, diplomats said on Monday, a finding which if proven would clash with Iran’s assertion its nuclear work is for civilian use.

The diplomats commented on a Times of London report about what it called a confidential Iranian technical document describing a four-year plan to test a neutron initiator, the part of a nuclear warhead that sets off an explosion.

VIENNA (Reuters) – The U.N. nuclear watchdog voted Friday to rebuke Iran for building a uranium enrichment plant in secret but Tehran rejected the move as “intimidation” which would poison its negotiations with world powers.

The resolution was the first by the 35-nation board of the International Atomic Energy Agency (IAEA) against Iran in almost four years, and a sign of spreading alarm over Tehran’s failure to dispel fears it has clandestine plans to build nuclear bombs.

VIENNA (Reuters) – Six world powers are demanding Iran immediately mothball a uranium enrichment site it hid for years in a resolution to be voted on by U.N. nuclear agency governors, calling it a message to Tehran to change its ways.

A defiant Iran denounced the resolution, expected to be put to a vote on Friday, as “counterproductive” to diplomatic efforts to defuse a standoff over its nuclear ambitions and accused the powers of “politicizing” the U.N. nuclear watchdog.

VIENNA (Reuters) – The U.N. nuclear watchdog chief Thursday criticized Iran’s blockage of a plan to divest it of possible nuclear bomb material as “disappointing.”

Under the deal drafted by Mohamed ElBaradei, Iran would send 75 percent of its low-enriched uranium (LEU) to Russia and France. There it would be made into special fuel for a Tehran reactor making medical materials, which will run out next year.

VIENNA (Reuters) – Iran’s demand for changes to a nuclear fuel deal is unacceptable because it could mean Tehran keeping enough enriched uranium for possible use in an atom bomb, the U.N. nuclear watchdog chief said in an interview.

Mohamed ElBaradei also told Reuters on Wednesday that U.N. inspectors had no proof of more covert nuclear sites in Iran but a newly revealed enrichment site made little sense for civilian or military ends and mistrust in Tehran’s behavior had grown.

VIENNA (Reuters) – Building a second uranium enrichment site is a “political message” from Iran that neither sanctions nor possible military attack will ever stop its nuclear programme, a senior Iranian official said on Tuesday.

In an interview, Ali Asghar Soltanieh, Iran’s envoy to the U.N. nuclear watchdog, said the agency’s concern Tehran may be hiding more nuclear work after it unveiled the enrichment site was wrong, unfair and a political judgment beyond its mandate.