The growing and deepening alliance between the mullahs of Iran and the America-bashing leader of Venezuela, Hugo Chávez, poses a serious threat to U.S. national interests, but the Obama administration has been behind the curve in appraising these risks and forging effective policies to counter them.

The administration’s neglect of the dangers in the Iran-Venezuela bonds assumes greater importance against the backdrop of the rising tensions in the Middle East. Iran continues to be a direct threat to U.S. national security, the security of our close ally, Israel, and other U.S. interests. As Iran accelerates its drive toward building a nuclear weapon in the face of growing U.S.-led sanctions, the probabilities grow of a major conflict in the region.

Countries that support Teheran, such as Venezuela, could be tempted to serve as proxies for Iran around the world and in coordination with Iran openly challenge the United States. Iranian government officials have already made statements to the effect that any response to aggression would include the closing of the Strait of Hormuz, the choke point through which a fourth of the world’s oil moves.

Venezuela, in sympathy with its friend Iran, could at the same time cut off its oil exports to the United States or take other steps to disrupt oil supplies.

Yet the administration has paid little attention to Venezuela’s tightening links with Iran and the consequences for U.S. security. The most glaring recent example is President Obama’s cavalier decision last year to delay construction of the Keystone XL pipeline, which would bring Canadian oil down to Gulf Coast refineries that now rely heavily on Venezuelan crude. Ending our energy dependence on Venezuela would take the oil weapon out of Chávez’s hands, in effect disarming him without firing a shot.

Hostile Iranian actions in the Western Hemisphere are not far-fetched, they are a reality. Iran is seeking to establish terrorist networks around the world, and it sponsored a terrorist attack in Buenos Aires in 1992. The bizarre plot by Iran against Saudi Arabia’s ambassador to Washington, disrupted last year, further illustrates the mullahs’ brazen intentions.

The chances of Venezuela serving as Iran’s surrogate in the hemisphere through terrorism or other coordinated action are increased by its chaotic state of affairs. Venezuela is in the midst of a make-or-break election that will determine the survival of its democracy amid continuing doubts about President Chávez’s health and a welcomed show of will by its diverse opposition groups. Divisions in Venezuela’s Russian-armed military, an inflation rate over 30 percent, a dilapidated oil infrastructure, widespread food and energy shortages, and soaring crime rates are all putting heavy pressure on President Chávez.

President Chávez may think he would benefit from redirecting attention away from his domestic troubles by uniting his followers and feeding his paranoid “anti-imperialist dreams” in a battle against the United States.

At the same time, Iranian-Venezuelan ties are steadily growing. Iranian President Mahmoud Ahmadinejad made a five-day visit last month to Venezuela and three other Latin American countries, his fifth trip to the region since 2005.

If Iran were to close the Strait of Hormuz in a conflict, global oil prices would skyrocket. Venezuela supplies about 10 percent of current U.S. imports of crude oil and petroleum products. In a scenario where the Strait is closed, a coordinated shutdown of Venezuela’s oil to the United States would be a double blow to the United States.

I call on the Obama administration to address promptly the threats to the United States should Venezuela use energy as a weapon. The president should:

• Issue an explicit warning to Venezuela that the United States would regard a cut off of oil exports in coordination with a belligerent Iran as a threat to U.S. national interests.

• Expand strategic energy agreements with Brazil and other countries in the hemisphere to help assure access to supplies of petroleum, refined products and ethanol in the event of a crisis.

• Immediately approve construction of the Keystone XL pipeline, as he is authorized to do under a recent law I sponsored, to supply Canadian crude to the Gulf Coast refineries that now depend on supplies from Venezuela.

U.S. Sen. Richard Lugar, R-Indiana, is the ranking member of the Senate Foreign Relations Committee.