Chavez severed relations with U.S. ally Colombia last week over Bogota's charges his oil exporting country allowed Colombian guerrillas to stay in camps.
He has since said Colombia was preparing a military attack. Colombia denies the charge, and most analysts say a war between the countries is very unlikely.
"I should tell you we have deployed units to defend our sovereignty in case of an aggression, air defense units, air units, infantry, special operations," Chavez said in a phone call to a state TV station, adding that a Colombian aircraft had violated Venezuela airspace for five minutes this week.
"We don't want to hurt anybody. We don't want to cause alarm in the population," said Chavez, who has seized on the dispute with Colombia to rally supporters ahead of parliamentary elections on September 26.
This week Venezuelan soldiers visited sites Colombia says are established military bases, but they found only derelict buildings, Chavez said. In one case, the coordinate given by Colombia led soldiers to a rock in a river, he said.
"Last night I said to the guys, "lift the rock," sure it's not a big stone, but you never know, there might be a tunnel," he said. "Maybe under the stone there is a tunnel and a camp, Vietnam-style."
On Sunday he threatened to cut oil supplies to the United States, who he says is behind the alleged plan to invade, in case of military aggression from Colombia. The threat is a common one for Chavez, but he has never followed through and oil and debt markets shrugged off the news.
The socialist leader said he believed the outgoing conservative government of President Alvaro Uribe, who he described as "obsessed," might still attack Venezuela, but said his Foreign Minister will meet with Colombia's new government, which takes office on August 7.
Close Uribe ally Juan Manuel Santos, a former defense minister who will become president next week, wants to improve relations with Venezuela because the festering dispute has cost Colombia billions of dollars in lost trade.
Chavez did not say where he had sent the forces, or how many were deployed. Colombian Foreign Minister Jaime Bermudez on Thursday promised no attack was planned.
Two years ago, Chavez ordered tanks to the border in protest at a Colombian bombing raid on a guerrilla base in Ecuador. It was never clear if the tanks were mobilized.
A former soldier, Chavez says he would not launch an offensive against another country, but has spent billions retooling his armed forces because he says the OPEC nation is vulnerable to a U.S.-backed invasion.
Venezuela has proposed a wide-reaching peace plan to end Colombia's four-decade civil war, saying it is a victim of violent groups that spill over the border. Uribe has wanted Chavez to take action against guerrillas he say launch dozens of attacks from Venezuela.
Chavez denies his government supports the rebels, but says he cannot take sides in the Colombia's war. He also recognizes that much of Venezuela's 1,375-mile (2,200-km) border with Colombia is porous and vulnerable.