The US military said Monday that 1,000 more soldiers would be sent to the Middle East, citing concerns about the threat from Iran following attacks on two tankers in the Gulf of Oman last week.

"The United States does not seek conflict with Iran," acting Defense Secretary Patrick Shanahan said, claiming that "the recent Iranian attacks validate the reliable, credible intelligence we have received on hostile behavior by Iranian forces and their proxy groups that threaten United States personnel and interests across the region."

The 1,000 extra troops will join the 1,500 soldiers sent in May after a similar set of attacks on tankers in the Gulf. The US and its regional allies also blamed Iran for carrying out those attacks.

Pentagon releases new images

Earlier, the US Department of Defense released several new photos that it said prove Iranian forces were behind the attacks on tankers in the Gulf of Oman on Thursday. Tehran has repeatedly denied involvement.

According to the Pentagon, the photos were taken from a Navy helicopter and show some of Iran's Revolutionary Guards removing a mine from near the Japanese-owned Kokuka Courageous tanker. A second photo purports to show a massive hole in the side of the Courageous, which the US said was caused by another mine.

"Iran is responsible for the attack based on video evidence and the resources and proficiency needed to quickly remove the unexploded limpet mine," the Defense Department said.

The UK has said that its own independent investigation corroborates that Iran was involved in the attack. The EU, however, has urged caution before jumping to conclusions.

Last week, the US military released a grainy video that it said proved Iran's culpability.

'Nuclear blackmail'

Iran said Monday that it would soon breach limits on how much uranium it is supposed to enrich, accusing Washington of "nuclear blackmail."

"We have quadrupled the rate of enrichment (of uranium) and even increased it more recently, so that in 10 days it will bypass the 300 kg limit," said Behrouz Kamalvandi, a spokesman for Iran's Atomic Energy Organization.

President Donald Trump pulled the US out of the 2015 Iran nuclear deal last year. Since then, US officials have been angling to get Tehran to sign a more restrictive agreement, imposing economic sanctions and moving more troops to the region to step up pressure.

es/amp (AP, AFP, Reuters, dpa)

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