Heavy shelling in Syria's Homs

Activists say Syrian government forces are intensifying their assault on opposition strongholds in the city of Homs. Thick smoke from the heavy bombardment covers the city's skyline in amateur footage said to be shot on June 12. Video said to be shot on June 11 in Homs purports to show a Syrian army vehicle explode in a roadside bombing by rebel forces. Reuters cannot independently verify the content of these videos, which were posted to social media websites. United Nations monitors said Syrian helicopters fired on rebel strongholds north of Homs on Monday. U.N. efforts to bring peace to Syria - where a 15-month-old uprising against Syrian President Bashar al-Assad has turned increasingly violent - have largely come to nothing, with both sides blaming the other for breaking the ceasefire. Sarah Sheffer, Reuters