Al-Monitor | Maxim A. Suchkov : Russia and Iran are deepening their military ties in a joint challenge to perceived US hegemony in the Middle East. The Russian Defense Ministry and the General Staff of the Iranian Armed Forces signed a memorandum of understanding that seeks to expand military ties between the two countries on Monday during Iranian Navy Commander Hossein Khanzadi�s three-day visit to St. Petersburg.

"This is the first memorandum of understanding of this kind, and it may be considered a turning point in the relations of Tehran in Moscow along the defense trajectory," Khanzadi said.

He added, "A joint Russian-Iranian exercise is expected to be held shortly in the Indian Ocean. The exercise may also be held in the northern part of the Indian Ocean, including in the Strait of Hormuz."

Why it matters: The memorandum is not legally binding and does not burden either party with additional �allied commitments.� However, it is important in at least two ways.

Read more here