Iran's President Mahmoud Ahmadinejad gestures upon his arrival at the international airport in Maiquetia, Venezuela on Sunday. Ahmadinejad will visit Venezuela, Nicaragua, Cuba and Ecuador as part of a tour aimed at showing off relationships with some of Tehran's close allies while tensions grow over the country's threats to block oil shipments in retaliation for tighter U.S. sanctions. (Ariana Cubillos/AP)

With his government increasingly isolated by sanctions and facing the U.S. Navy close to home, Iranian President Mahmoud Ahmadinejad flew Sunday to Venezuela to meet with a like-minded leader who shares his goal of challenging the United States, President Hugo Chavez.

The arrival of Ahmadinejad in the Venezuelan capital, to be followed by a swing this week through Nicaragua, Cuba and Ecuador, allows Iran to show that it still has friends and economic partners despite sanctions designed to cripple its nuclear program. Back home, Iran’s currency, the rial, has steadily lost ground, buffeting importers, while tensions have risen over the country’s threats to close the Strait of Hormuz, through which 20 percent of the world’s crude oil supply passes.

To be sure, in Chavez, Ahmadinejad has an enthusiastic supporter who has vocally backed Iran’s nuclear program, taken sides with Tehran against Israel and adhered to the Iranian government’s line that domestic critics of its policies are little more than CIA stooges.

“What the empire does is make you laugh in its desperation to do something they will not be able to do: dominate the world,” Chavez said Sunday as he resumed his weekly television show, “Hello, Mr. President,” which had been suspended since June as he recovered from surgery to remove a cancerous tumor.

“We are free,” said Chavez, who told viewers that he would meet with Ahmadinejad on Monday. “The people of Latin America will never again kneel, dominated by the imperial Yankee.”

Before departing Tehran on Sunday morning, Ahmadinejad told the semiofficial Fars News Agency that strong ties with Latin America were vital toward “battling the hegemonic systems” of the United States and its European allies.

“We will discuss the hegemonic system’s efforts to interfere in countries and establish its military presence there,” he told Fars, using language similar to that employed by Chavez to appeal to his most radicalized followers. Other Iranian officials also have cast the trip as a sign that sanctions had failed.

Iran has not been isolated, Esmail Kowsari, a former general who serves on parliament’s national security and foreign policy committee, told Fars on Sunday. He added that “one of the signs is the expansion of trade between Iran and other countries, particularly the Latin American ones.”

But Ecuador, Nicaragua and Cuba have small economies with little to offer Tehran as it searches for a tangible way to ease the impact of American sanctions. And Venezuela imports mainly from its neighbors while exporting oil, like Iran, a fellow member of the Organization of the Petroleum Exporting Countries .

Ahmadinejad is not visiting Brazil, the world’s sixth-largest economy, nor the bigger countries in the region, which have diverse economies but also pragmatic diplomatic and economic ties with the United States.

“There are a handful of countries, including a small number of countries in Latin America, that have been willing to establish warm relations with the Iranian government because of shared objectives,” said Cynthia Arnson, director of the Latin America program at the Washington-based Woodrow Wilson Center, which has closely followed Iran’s diplomatic initiatives in the region. “Most of that agenda is driven by antipathy toward the United States and a desire to confront U.S. power.”

The Obama administration has recently voiced concern about Iran’s efforts to increase its influence in the region.

In a rare interview with a Venezuelan newspaper, El Universal, President Obama said in December: “It is up to the Venezuelan people to determine what they gain from a relationship with a country that violates universal human rights.”

“Here in the Americas,” he added, “we take Iranian activities, including in Venezuela, very seriously and we will continue to monitor them.”

Still, high-ranking administration officials have said that although Iran has made an effort to play a bigger role in the region, it has fallen short. Close diplomatic ties remain limited to Chavez, Cuba’s communist government and countries with little economic clout. Pledges by a cash-strapped Iran to build a range of big-ticket projects in the region, including factories, ports, refineries and dams, have failed to materialize.

“We have no evidence that Iran’s efforts to enhance outreach to Latin America is gaining momentum,” a high-ranking Obama administration official, speaking on the condition of anonymity to discuss the matter freely, said in a phone interview. “The record is lots of agreement on paper, little that follows through in terms of concrete results.”

When it comes to Venezuela, though, it has not been for lack of trying.

Chavez has visited Iran nine times since taking office in 1999, and Ahmadinejad has made five visits to Venezuela since 2005. Washington has been watching the budding relationship closely, taking what Obama told El Universal were “a number of significant and effective steps to indicate our concern to the Venezuelan government.”

Those included the imposition of sanctions last year against Venezuela’s state-owned oil company after it shipped reformate, a gasoline blending component, to Iran. The Venezuelan Military Industries Co. also was sanctioned for dealings with Iran. Two years earlier, the U.S. Treasury imposed sanctions on the subsidiary of an Iranian bank in Venezuela, saying it was helping fund Iranian weapons development.

Then, on Sunday, the State Department said Venezuela’s top diplomat in Miami, Consul General Livia Acosta, has been told that she must leave the country by Tuesday. No explanation was given. But in December, a documentary on the Spanish-language Univision network presented evidence supporting allegations that Acosta and officials from Iran and Cuba were plotting a cyberattack on the United States. Venezuela has not responded to the expulsion order.

“We do pay attention,” the high-ranking U.S. official said. “And the United States has not hesitated to act when there’s evidence of Iranian malfeasance. And the bar is pretty low.”

Correspondent Thomas Erdbrink in Tehran contributed to this report.