Patrick Shanahan
Patrick ShanahanReuters

Acting US Defense Secretary Patrick Shanahan said on Monday that he approved the deployment of a US carrier strike group and a bomber task force to the Middle East because of "indications of a credible threat" by Iran.

Shanahan wrote on Twitter that he approved the decision to send the USS Abraham Lincoln carrier strike group and a US Air Force bomber task force to the area on Sunday.

The decision “represents a prudent repositioning of assets in response to indications of a credible threat by Iranian regime forces,” he wrote.

“We call on the Iranian regime to cease all provocation. We will hold the Iranian regime accountable for any attack on US forces or our interests,” added Shanahan in a second tweet.

National security adviser John Bolton announced the deployment on Sunday night, saying it was meant to send a clear message to Iran that any attack on US interests or its allies will be met with “unrelenting force.”

On Monday, it was reported that a significant portion of the information about Iran's preparations for a terror attack against a US target or its Gulf allies was obtained by Israeli intelligence, especially the Mossad.

Senior Israeli officials told Channel 13 News that the information obtained by the Mossad and other Israeli intelligence agencies was transferred to the Americans and was part of the basis for the American decision to reinforce their forces, sending another aircraft carrier to the Gulf.

Tensions have risen between the US and Iran over the past year, after President Donald Trump withdrew from the 2015 nuclear deal between Iran and world powers.

The US has since imposed two rounds of sanctions on Iran, the latest of which went into effect in early November. Those sanctions aim to reduce Iran’s oil exports to zero in a bid to curb the Islamic Republic’s missile program and regional influence.

In addition, Trump recently designated the Islamic Revolutionary Guards (IRGC) as a foreign terrorist organization.

In the last few years there have been several close encounters between Iranian and American vessels in the Persian Gulf.

Recently, a commander in the Iranian Revolutionary Guards threatened US bases in Afghanistan, the UAE and Qatar, as well as US aircraft carriers in the Gulf. These bases, he said, are within range of Iranian missiles which have a range of 700 km (450 miles).