Former US president Barack Obama has warned that the war on Iran has left the US “more vulnerable” as the Islamic Republic continues to keep the Strait of Hormuz closed, effectively holding “veto power” over the strategic waterway.

Speaking at a campaign rally in suburban Atlanta, Georgia, on Wednesday, Obama slammed US President Donald Trump’s handling of the unprovoked 40-day war of aggression launched jointly with Israel against Iran on February 28.

“I didn’t have to fire any missiles. I engaged in diplomacy,” Obama said, criticizing Trump’s hostile policy against Iran, eight months after the war, whose costs ballooned to $47 billion, according to official figures.

During the aggression, Iran defended itself by striking US bases and assets in West Asia.

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“Our allies and bases have been attacked. Americans have been killed. Hundreds of Americans have been wounded. We have run down our stock of missiles, making us more vulnerable, and Iran now has veto power over the Strait of Hormuz,” Obama added during his speech delivered as part of his cross-country campaign tour before next week’s midterm elections, a vote that could shape the final two years of Trump’s presidency.

This is the “reason why the price of oil is up,” the former president stressed, referring to the closure of the Strait of Hormuz, through which roughly one-fifth of global oil demand passes. The waterway is one of the world's most strategically important maritime chokepoints.

Iran has so far refused to ease its restrictions on transit through Hormuz, saying the key international energy waterway will be fully reopened once the US permanently ends its aggression and lifts its maritime blockade and sanctions against the Islamic Republic.

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Under Obama, the US signed the landmark nuclear agreement with Iran, officially known as the Joint Comprehensive Plan of Action (JCPOA), in 2015 after 20 months of marathon negotiations. The other signatories were China, France, Germany, Russia, and the United Kingdom.

Under the agreement, the US and the EU agreed to remove anti-Iran sanctions imposed over the years in exchange for Iran limiting its uranium enrichment and reducing its existing stockpile.

However, on May 8, 2018, then US president Trump officially announced that he was unilaterally withdrawing the US from the JCPOA and imposed the “strongest sanctions in history” on Iran under the so-called “maximum pressure” campaign.