BBC News with Iain Purdon

The American Republican presidential candidate Mitt Romney has said the United States has a

solemn

duty to prevent Iran from developing nuclear weapons. Addressing an audience in Jerusalem, he said the US recognized Irael's right to defend itself and that the two countries should employ any and all measures to prevent Iran from achieving its aims.

"When Iran's leaders deny the Holocaust, or speak of

wiping this nation off

the map, only the naive – or worse – will dismiss it as an excess of

rhetoric

. Make no mistake: the ayatollahs in Tehran are testing our moral defenses. They want to know who will object, and who will look the other way. My message to the people of Israel and the leaders of Iran is one and the same: we will not look away.”

Government forces in Syria have again been using heavy weapons to pound opposition strongholds in Aleppo. Troops are trying to push into rebel-held neighborhoods and there has been fierce fighting. Ian Pannell reports from Aleppo.

We are getting reports again, but cannot

verify

them. A very heavy fighting near the old fort, this is pretty much in the central part of Aleppo. State media are certainly saying that there has been a quoted major breakthrough in the area, not sure what they think that is and lots of rumors that they are nothing stronger in there that perhaps the military do not launch an offense in the countryside as well because of cost. Many of the fighters came from the countryside and may be attacking and take them out.