North Korean leader Kim Jong Il reviewed a massive military parade in central Pyongyang on Monday as the communist state marked the 60th anniversary of its ruling party with vows to "mercilessly crush" American imperialists if they attack. After thousands of goose-stepping soldiers, some with bayonet-tipped rifles, entered Pyongyang's main plaza in neat columns, Kim appeared at the podium, sparking deafening applause from the troops and audience members while hundreds of balloons were released into the air, North Korean TV showed. Soldiers repeatedly shouted "Long live!" and Kim responded by clapping his hands and waving. "With undefeatable military strength, our People's Army will firmly safeguard the party and the socialist fatherland," Vice Marshal Kim Il Chol told the crowd in televised comments. "If US and Japanese imperialists and their followers ultimately ignite the fire of war on this soil, we will mercilessly crush the aggressors and achieve the historic accomplishment of reunification of the fatherland." Washington has repeatedly denied it has any intention to invade and said it recognizes the North's sovereignty.