The previously reported Iran-Russia-China joint naval drills have kicked off Thursday in Iran's increasingly crowded southern waters, as the United States continues expanding its military presence in the Arabian Sea.

Iranian Navy Rear Admiral Hassan Maqsudlu has made it clear that part of the purpose of the exercise is to "prevent any unilateral action in the region" - a clear challenge to Washington and the Trump-ordered ongoing Pentagon build-up of aerial and naval assets in the region. Iranian state TV has made it a point to widely publicize the drills, given it has Russia in its corner. Watch:

The drills are primarily taking place in the the key oil transit chokepoint Strait of Hormuz, as well as the Gulf of Oman, and the northern Indian Ocean.

The joint exercise been long planned, held annually since 2019, and usually also include China - but by appearances Beijing is taking a far backseat in this one, with little reported presence.

More footage of elite Islamic Revolutionary Guard Corps commandos deploying as part of the games:

There have also been reports of missile preparedness drills in some parts of Iran, a continuation of similar activity from earlier this month, amid the standoff with the US.

Reuters detailed the notice to airmen went to effect starting Wednesday: "Iran issued a notice to airmen (NOTAM) that it plans rocket launches in areas across its south on Thursday from 330 GMT to 1330 GMT, the U.S. Federal Aviation Administration website showed on Wednesday."

"The Islamic Republic of Iran has faced threats, noise, propaganda and the presence of extra-regional fleets in West Asia for 47 years," Iran’s Navy Commander Rear Adm. Shahram Irani warned. "The presence of extra-regional fleets in West Asia is unjustified."

“If the extra-regional fleet feels it has come with power, it should know that the Iranian people will confront them with greater power,” he added. “The faith of the people and missiles are the Islamic Republic of Iran’s deterrent weapons against the enemy.”

The War Zone publication gives some further details:

As Iranian and Russian officials gathered Wednesday aboard the Russian corvette Stoiky, a top Iranian official issued a new threat against the growing U.S. Navy presence in the region, which includes the Abraham Lincoln CSG and at least eight other surface combatants. The Ford could arrive in the region in the next four or five days given its location posted by the MarineTraffic ship tracking website. The Navy said only that the ship is now in the Atlantic Ocean.

If the US were to launch a 'surprise' attack on Iran, it remains unlikely that either Russia or China would come to Tehran's direct aid and engage militarily with Washington. However, it's possible more Chinese and Russian ships would be sent to patrol flashpoint waters, making things more delicate and difficult in terms of US Navy maneuvering and firing. 

At the very least, Moscow and Beijing would team up to issue a UN Security Council condemnation, and would seek to rally the globe against another Iraq-style war in the Middle East, with likely disastrous consequences for the whole region.