After days of heated barbs exchange back and forth between Washington and Tehran, Iran's elite Islamic Revolutionary Guard forces are expected to begin a major exercise in the Persian Gulf as soon as the next 48 hours, which could be aimed at demonstrating their ability to shut down the Strait of Hormuz, CNN reports citing two US officials.

"We are aware of the increase in Iranian naval operations within the Arabian Gulf, Strait of Hormuz and Gulf of Oman. We are monitoring it closely, and will continue to work with our partners to ensure freedom of navigation and free flow of commerce in international waterways," Captain William Urban, chief spokesman for US Central Command, told CNN.

The Strait of Hormuz - a strategically critical passageway linking the Persian Gulf to the Arabian Sea which is crucial to shipping of global energy supplies - has emerged as a focal point in the escalating war of words between presidents Trump and Rouhani, after Iran threatened to block off the Persian Gulf if the US proceeds with fully implementing oil export sanctions on Iran.

Officials told CNN that while the US sees no immediate signs of hostile intent from Iran, the IRGC show of force has US military intelligence "deeply concerned" for three fundamental reasons according to officials:

The exercise comes as rhetoric from the IRGC towards the US has accelerated in recent days.

It appears the IRGC is ramping up for a larger exercise this year than similar efforts in the past.

The timing is unusual. These types of IRGC exercises typically happen much later in the year.

In the US military's assessment, the IRGC has assembled a fleet of more than 100 boats, many of them small fast moving vessels. It's expected Iranian air and ground assets including coastal defensive missile batteries could be involved, while hundreds of Iranian troops are expected to participate and some regular Iranian forces could be involved as well.

The IRGC exercise comes as the US has only one major warship, the USS The Sullivans inside the Persian Gulf, several officials say. Other US warships are nearby and there are numerous combat aircraft in the region. The US military has been trying to encourage other nations in the region, especially Saudi Arabia to take a strong line on keeping the Gulf open in the face of rising Iranian rhetoric. They have also expressed concern about keeping open the waterways off Yemen where Iranian backed rebels have attacked oil tankers.

Defense Secretary James Mattis, responding to rising Iranian rhetoric said on Friday, "Iran has threatened to close the Strait of Hormuz. They've done that previously in years past. They saw the international community put -- dozens of nations of the international community put their naval forces in for exercises to clear the straits."

And the punchline:

"Clearly, this would be an attack on international shipping, and -- and it would have, obviously, an international response to reopen the shipping lanes with whatever that took, because of the world's economy depends on that energy, those energy supplies flowing out of there."

And with the public response to any attack on Syria now virtually nil after two consecutive military strikes, if Trump feels he is in urgent need of an international distraction from mounting domestic problems, namely the upcoming conclusion of the Mueller probe which now includes questions about obstruction of justice, Trump may have no choice than to aim for Iran... and outcome Israel would be delighted to assist with.