Opposition activists say Homs faces humanitarian catastrophe as essentials run out •
Assad sends a brigade of T-72 tanks to Homs as reinforcements Wednesday afternoon •
Turkish FM Davutoglu calls for international coalition to stop Assad's deadly crackdown •
He is to meet Secretary Clinton in Washington and push a new Erdogan plan for Syria •
Russian PM Putin Wednesday cautioned against outside interference in the Syrian conflict "like a bull in a china shop" •
Iranian ambassador to Moscow says his country can hit US military forces anywhere in the world if attacked by them •
Investigative judges in Cairo say US and Egyptian pro-democracy activists could face up to five years jail •
The case has clouded Egyptian-US relations and threatens US aid •