President Asif Ali Zardari has called on the nation to unite behind the armed forces as they pressed a new offensive against Taliban militants on Thursday north of the capital Islamabad. He further said the nation was facing a "critical hour" in its fight against Islamic militants linked to Al-Qaeda, and that the military offensive in the scenic Swat region was vital to protect the constitution. "Time has come for the entire nation to give pause to their political differences and rise to the occasion and give full support to our security forces," Zardari said in a statement late Wednesday. "This is the only way to demonstrate our will, to keep Pakistan as a moderate, modern and democratic state where the rights of all citizens are protected," he said.