Beyond Russia, Venezuela is also considering a venture with Iran, its closest ally outside Latin America, to build a remotely piloted patrol aircraft. Gen. Raúl Isaías Baduel, the Venezuelan defense minister, recently told reporters that the project to build 20 of the aircraft could be used to bolster border surveillance and combat environmental destruction in Venezuela. Venezuela is also strengthening military ties with Cuba, sending officers and soldiers there for training.

Supporters of the arms buildup contend that under Mr. Chávez, who has been in power for eight years, Venezuela has spent proportionately less on its military in relation to the size of its economy than the United States or than other South American countries like Chile and Colombia.

In 2004, the last year for which comparative data were immediately available and before Venezuela’s arms buildup intensified, overall defense spending by Venezuela, including arms contracts, was about $1.3 billion and accounted for about 1.4 percent of gross domestic product, compared with 4 percent in the United States and 3.8 percent in Colombia, according to the Stockholm International Peace Research Institute, which tracks military spending.

Doubts persist as to how powerful Venezuela’s armed forces have become in a regional context, even as they acquire new weapons. Military experts here say pilots in the air force still need training to start flying their new Russian fighters. And in terms of troop strength, Venezuela’s 34,000-soldier active-duty army still lags behind the armies of Argentina and Brazil, with about 41,400 and 200,000 members respectively, according to GlobalSecurity.org, a Web site that compiles data on military topics.

Pro-Chávez analysts also say the president is less adventurous in relation to military policy outside Venezuela than predecessors like Luis Herrera Campíns, who supported Argentina in the Falklands War in 1982 to detract attention from a decline in oil revenue and climbing inflation.

But critics of the arms purchases say they are being made with little participation from or discussion with the National Assembly, which recently allowed Mr. Chávez to govern by decree for 18 months.

Ricardo Sucre, a political scientist at the Central University of Venezuela, said that the lack of transparency of the weapons contracts had heightened concern that Mr. Chávez could be arming parts of the army, the new civilian reserve and partisans like the Frente Francisco de Miranda, a pro-Chávez political group, that would be loyal to him in the event of fractures within the armed forces.