Hong Kong CNN  — 

China, Russia and Iran began a four-day joint military exercise in the Indian Ocean and Gulf of Oman on Friday amid ongoing friction in the economically important region between Tehran and Washington.

The Gulf of Oman has been a focal point of geopolitical tensions in 2019, after two oil tankers were attacked in the narrow strait in June by an unidentified party. The US blamed Iran for the attack but Tehran denied the allegations. Then in July, Iran detained a British oil tanker, the Stena Impero, for two months.

The vessels planned to leave Iran’s Chabahar port in the Gulf of Oman, before being deployed across areas in the north of the Indian Ocean, Second Rear Admiral Gholamreza Tahani said earlier, according to Iran’s state-run Press TV.

Tahani said the exercise will cover 17,000 square kilometers and consist of “various tactical exercises,” which include target practice and rescuing ships from assaults and fires.

“َAmong the objectives of this exercise are improving the security of international maritime trade, countering maritime piracy and terrorism, exchanging information regarding rescue operations and operational and tactical experience,” Tahani added.

Russian President Vladimir Putin, Chinese President Xi Jinping and Iran's President Hassan Rouhani attend a meeting of the Shanghai Cooperation Organisation (SCO) Council of Heads of State in Bishkek on June 14.

The joint drills also serve as a signal to the world that relations between Tehran, Moscow and Beijing have reached a “meaningful” level, Tahani said. He added that it was the first time Iran has held a joint exercise with two major world naval powers at this scale.

Beijing’s defense spokesman Wu Qian said Thursday that the drill was a “normal military exchange” between the three armed forces and was in line with international law and practices.

The drill was not necessarily connected with the regional situation, Wu added.

“The upcoming naval drills are aimed at deepening exchange and cooperation among the navies of the three countries, and displaying the three sides’ strong will and capabilities to jointly maintain world peace and maritime security, while actively building a maritime community with a shared future,” he said.

Speaking at a news conference on Wednesday, Iranian Armed Forces Brig. Gen. Abolfazl Shekarchi said it was “important and vital” that security was established in the Indian Ocean and the Sea of Oman.

“The Indian Ocean and the Sea of Oman are among the world’s key trade routes and many countries commute in the (two) regions and therefore establishing security there is important and vital,” Shekarchi said.

The Gulf of Oman connects to the Strait of Hormuz, through which roughly 30% of the world’s sea-borne crude oil passes. Shekarchi added that the military exercises would be aimed at increasing power and experience to ensure international trade security in the region.

The joint drills are likely to be perceived as provocative by Washington. Earlier this year US President Donald Trump proposed sending a US-led naval mission to the Gulf of Oman to protect economic interests in the region.

In a Twitter post on Thursday, Trump took aim at Iran, Russia, and the Syrian government led by President Bashar al-Assad, warning the three countries against military action in Syria.

“Russia, Syria, and Iran are killing, or on their way to killing, thousands of innocent civilians in Idlib Province. Don’t do it!” Trump wrote.