A showdown between Iran and the United States over Tehran's threats to close the strategic Strait of Hormuz to oil tankers worsened Thursday with warships from each side giving weight to an increasingly bellicose exchange of words.

Iran's Revolutionary Guards rejected a warning that the U.S. military would "not tolerate" such a closure, saying they would act decisively "to protect our vital interests."

The Obama administration has hit two men with sanctions for allegedly laundering money on behalf of Mexican and Colombian drug cartels.

The move blocks any assets in the U.S. belonging to Lebanese-Colombian nationals Jorge Fadlallah Cheaitelly and Mohamad Zouheir El Khansa, and blocks Americans from doing business with them.

The U.S. State Department on Wednesday urged Syria to allow Arab monitors to observe as many anti-regime protests as possible and provide unfettered access to members of the opposition.

However, it said it was premature to comment on the first day of monitoring on Tuesday, unlike France which said the monitors were denied the chance to see the reality in the flashpoint city of Homs, where many civilians have been reported killed.

The U.S. warned Iran on Wednesday against any attempt to disrupt shipping in the Strait of Hormuz, after Tehran issued threats over the vital oil route, as France called on Iranian authorities to respect international law and navigation rights.

"Interference with the transit ... of vessels through the Strait of Hormuz will not be tolerated," said Pentagon press secretary George Little.

The number of sexual assaults reported at the country's prestigious military academies rose sharply for the second year in a row, according to a Pentagon report issued Tuesday.

A total of 65 sexual assault cases were reported at the three academies in 2010-11 compared to 41 reports in the previous academic year, the report said.

The United States on Tuesday accused Syria of having intensified attacks against its people before Arab observers arrived in the country to monitor a deal to end nine months of deadly violence.

"It was a horrible situation where the violence spiked over the course of several days. We obviously condemn this escalation of violence," State Department deputy spokesman Mark Toner told reporters.

Israel's defense ministry said on Sunday that the United States has agreed to provide it with an additional 235 million dollars to finance its rocket defense system.

"The aid from the American Congress is a supplementary step in the reinforcement of Israeli-American relations in the area of defense," Defense Minister Ehud Barak said in a statement.

The United States is mulling a far more subdued role in Iraq after pulling its troops out, and has no intention to send its forces back in despite a spike in violence, The New York Times reported Sunday.

U.S. officials told the Times that President Barack Obama was adamant that the United States would not send troops back to Iraq, adding that even an American military presence likely would not have prevented the political crisis and coordinated attacks plaguing the country days after a U.S. pullout.

Iran denied on Sunday it is harboring an alleged al-Qaida fundraiser who has a $10-million U.S. bounty on his head, with the foreign ministry calling the claim "utterly baseless."

The U.S. charge that Iran was protecting Syrian-born Ezedin Abdul Aziz Khalil was part of an "inept" attempt to implicate Iran in the September 11, 2001 attacks on the United States, ministry spokesman Ramin Mehmanparast said, according to the website of the state broadcaster IRIB.

The suicide bombings which struck Damascus Friday killing 40 people must not hamper the Arab League monitoring mission in Syria, a U.S. official said Friday, condemning the attacks.

"It is crucial that today's attack not impede the critical work of the Arab League monitoring mission to document and deter human rights abuses with the goal of protecting civilians," State Department spokesman Mark Toner said.