Armenians have celebrated the 20th anniversary of their country's independence from the Soviet Union with a military parade in the capital, Yerevan.

Huge crowds greeted thousands of marching troops Wednesday in Yerevan's Republic Square, where tanks, helicopters, fighter planes, missiles and spy drones were on display.

Addressing the parade, Armenian President Serzh Sarkisyan said Armenia had made a huge leap forward in the past two decades but added there is still much to be done.

Numerous world leaders sent congratulatory messages to Mr. Sarkisyan to mark the occasion, including U.S. President Barack Obama, Turkish President Abdullah Gul, Pope Benedict and United Nations Secretary-General Ban Ki-moon.

Armenia has faced political and military turmoil since proclaiming its independence on September 21, 1991, including several disputed elections, the aftermath of a devastating 1988 earthquake, and war with Azerbaijan over the breakaway majority Armenian enclave of Nagorno-Karabakh.

Armenia and Azerbaijan fought a war over the region after the collapse of the Soviet Union that left 35,000 people dead and displaced about 1 million others. The war ended in a cease-fire in 1994, and Nagorno-Karabakh has since been under the control of Armenian forces.

Tensions along the border remain high, and repeated international efforts to broker a peace deal have failed.