By Francois Murphy

VIENNA, Feb 26 (Reuters) - The United States hopes talks with Iran in Geneva will produce an agreement to prevent Tehran acquiring nuclear weapons, and President Donald Trump has amassed forces in the Middle East to increase pressure on the Islamic Republic to reach a deal.

WHAT IS AT STAKE?

Iran has over decades developed an advanced and large-scale uranium enrichment programme. While enriched uranium can be used as fuel in power plants at various purity levels, at high levels it can be used to make nuclear weapons.

Iran and the United States made "significant progress" in talks in Switzerland on Thursday, mediators said, after the latest round of negotiations to avert a war between the longtime foes, and agreed to further discussions next week in Austria.

The Oman-mediated negotiations follow repeated threats from Donald Trump to strike Iran, with the US president last Thursday giving Tehran 15 days to reach a deal.

The United States and Iran are set to hold indirect talks in Switzerland on Thursday aiming to strike a deal to avert fresh conflict and bring an end to weeks of threats.

The new round of negotiations in Geneva comes after the US carried out a massive military build-up in the region and President Donald Trump repeatedly threatened to strike Iran if a deal is not reached.

In his State of the Union address on Tuesday, Trump accused Iran of "pursuing sinister nuclear ambitions".

GENEVA, Feb 26 (Reuters) - Iran and the U.S. hold the latest round of talks in Geneva on Thursday aimed at resolving their longstanding nuclear dispute and averting new U.S. strikes on Iran following a large-scale military buildup.

The two countries renewed negotiations this month, hoping to tackle a decades-long stand-off over Tehran's nuclear program, which Washington, other Western states and Israel believe is aimed at building nuclear arms. Tehran denies this.

WASHINGTON, Feb 25 (Reuters) - The U.S. Central Intelligence Agency has posted on social media new Farsi-language instructions for Iranians wishing to securely contact the spy service.

The CIA recruitment effort comes amid a massive buildup of U.S. military forces in the Middle East that President Donald Trump could order to attack Iran if talks with the U.S. set for Thursday fail to reach a deal on Tehran's nuclear program.

By Kanishka Singh

WASHINGTON, Feb 25 (Reuters) - President Donald Trump said Wednesday that two Muslim Democratic U.S. Representatives, Ilhan Omar of Minnesota and Rashida Tlaib of Michigan, should be "institutionalized" and sent back to "where they came from," a day after they had a heated exchange with him during his State of the Union address.

During Trump's speech on Tuesday, Tlaib, a Palestinian American, and Omar, a Somali American, criticized Trump as he touted his administration's hard-line immigration crackdown and its immigration enforcement actions.

WASHINGTON, Feb 25 (Reuters) - The United States sees evidence that Iran is trying to rebuild its nuclear program after U.S.-led strikes against Iranian nuclear sites in June, Vice President JD Vance said on Wednesday.

"The principle is very simple: Iran cannot have a nuclear weapon," Vance told reporters, a day ahead of talks in Geneva between U.S. and Iranian delegations.

(Reporting by Steve Holland; Editing by Chris Reese)

By David Brunnstrom

WASHINGTON, Feb 25 (Reuters) - U.S. President Donald Trump briefly laid out a case for a possible attack on Iran in his State of the Union speech to Congress, saying he would not allow what he called the world's biggest sponsor of terrorism to obtain a nuclear weapon.

Trump called Tehran's support for militant groups, the killings of anti-government protesters in January and the country's missile and nuclear programs threats to the region and the United States.

Here are some questions and answers about his statements:

Prince Harry and Meghan Markle arrived on Wednesday in Jordan, where they met with Syrian refugees at the Zaatari camp and Palestinian children evacuated from the Gaza Strip.

King Charles III's younger son and his wife "met young refugees... and joined children in football, art and music", the United Nations refugee agency UNHCR said in a post on X.

Jordan opened the Zaatari camp located north of Amman in 2012, a year into the war in neighbouring Syria, to host people fleeing the conflict.

Today it is home to some 45,000 refugees.

Feb 25 (Reuters) - U.S. President Donald Trump's special envoy Steve Witkoff told a private gathering on Tuesday that the administration is demanding any nuclear deal with Iran should remain in effect indefinitely, Axios reported on Wednesday, citing a U.S. official and two others with knowledge of the comments.