Pakistan is holding its first Republic Day parade in seven years amid tight security.
The Pakistan Day parade in the capital had been canceled since 2008 amid fears of militant attacks.
The military has cut mobile phone voice and text communications across Islamabad.
The army has launched a massive offensive against the Pakistani Taliban in the country's lawless tribal areas.
Fighter jets have pounded positions in the Tirah Valley in the Khyber region over the last few days.
The military said on March 22 that it had killed 80 "terrorists" in heavy clashes and suffered seven casualties.
Pakistan Day commemorates March 23, 1940, when the Muslim League demanded the establishment of separate nations to protect Muslims in the then British India.
