CARACAS, Venezuela (AP) – Venezuela plans to obtain air defense missiles to guard strategic sites such as oil refineries and major bridges against any air strike, a top military adviser to President Hugo Chavez said Tuesday.

General Alberto Muller said Venezuela is looking to buy surface-to-air missile systems from Russia or another country to defend “strategic points in the country.”

“They are for air defense,” Mr. Muller told The Associated Press in a telephone interview. “They are not for attacking anybody.”

Mr. Chavez, a close ally of Cuban leader Fidel Castro, has repeatedly warned against a possible American invasion, and his government is bolstering military defenses in Venezuela, one of the world’s largest oil exporters. American officials insist they have no such military plans, but Chavez insists Venezuelans must be ready just in case.

Russia’s Interfax-Military News Agency reported Tuesday that between 10 and 12 Tor-M1 missile systems could be supplied to the South American country.

Mr. Chavez said last August that Venezuela planned to install an advanced air-defense system with missiles capable of shooting down approaching enemy warplanes, and said his military was looking at systems produced by Russia, Belarus and Iran.

John Pike, a defense analyst at GlobalSecurity.org, a think tank based in Alexandria, Va., said such systems usually have a limited range and are not meant for offensive purposes.

“Typically, a surface-to-air missile, if it’s a fixed defense system, is going to have a range of several miles. It might have a range of a couple dozen miles, but that’s about it,” Mr. Pike said.

The Tor-M1 system consists of eight missiles mounted on a launch vehicle. The system can identify up to 48 targets and fire at two targets simultaneously at a height of up to 20,000 feet.

Other military deals by Venezuela already have concerned American officials, who see the left-leaning Mr. Chavez as a threat to stability in Latin America.