Hundreds of thousands of Iranians marked 41 years since the Islamic Revolution in the countryas tensions with the U.S. and the world remain high.Iranian President Hassan Rouhani spoke in Tehran's Azadi Square Tuesday to denounce the United States.He also called on people to vote in upcoming elections.Last month, Iran's Guardian Council barred thousands of candidates from running, including about 90 current lawmakers.Iran considers many people voting in elections a show of confidence in the country's cleric rulers.Rouhani told a crowd, "We should not withdraw from the ballot boxes."However, a number of recent incidents have added to continued international pressure on the nation of more than 84 million people.Iran remains under international sanctions after the U.S. withdrew in 2018from an international agreement meant to limit Iran's nuclear weapons program.The administration of U.S. President Donald Trump objected to the deal.Officials said it did little to prevent Iran from developing nuclear materials or missiles.Early this year, the commander of the Revolutionary Guard's Quds Force, Qassem Soleimani, was killed in a U.S. strike in Baghdad.Large gatherings for his funeral, however, were marred by Iran's shooting down of a Ukrainian passenger jet.One hundred seventy-six people were killed.The Iranian government then refused for days to admit that it had shot down the plane with missiles.Iran and Ukraine continue to dispute the investigation of the downed airplane.In November, Iranians blocked traffic in major cities to protest an increase of 50 percent in government-set gasoline prices.The government reacted with a campaign against protesters.The human rights group Amnesty International said that more than 300 people were killed in the unrest.The government did not release the number of deaths, but lawmakers said thousands of people were detained.Tensions increased again in January after the killing of Soleimani,who had been linked to the use of roadside bombs used to attack American soldiers in Iraq.The Quds Force that he led is also involved in Middle East conflicts in Syria, Yemen and other places.The Islamic Revolution in Iran began after Shah Mohammad Reza Pahlavi fled the country in January 1979.Islamic cleric Ayatollah Ruhollah Khomeini then returned from exile in Paris to become the country's leader.In November of that year, Iranians, angry that the Shah was receiving medical treatment in the U.S.,seized the U.S. embassy and took more than 50 hostages.Iran held the hostages for more than one year before releasing them in early 1981.