Israel's top Air Force officer said Wednesday that Russian S-300 air defense systems, if or when deployed by Iran, would constitute more of "a strategic issue than an operative issue" because it would embolden Tehran to "even more aggressive" behavior.

"It's a huge challenge," Maj. Gen. Amir Eshel, Israel Air Force commander conceded, when asked about a May 26 announcement — following meetings in Moscow between Russian and Iran officials — that the systems would be delivered to Iran at an unspecified time.

"But it's more a strategic issue… because whoever has the S-300 feels protected. He can allow himself to do things even more aggressively, because he thinks he's defended," Eshel told Defense News.

He added, "But operatively speaking, every challenge presents an opportunity."

In an address Wednesday at the Fisher Institute for Air & Space Strategic Studies, Eshel did not specifically single out the prospective S-300 deliveries to Tehran. He noted, however, the expanding threat of surface-to-air missiles in the hands of Israel's enemies.

"I tell you now, and obviously this is based on all kinds of assessments we've done … that the enemy cannot stop our Air Force.

"They can complicate our activities, but it will be pinpoint complications here and there. But to stop this offensive machine that we have cannot be done."

A day earlier, following a meeting with Iranian Deputy Foreign Minister Hossein Amir-Abdollahian, Yevgeny Lukyanov, deputy head of Russia's security council, was quoted by Russian news agencies as saying, the "The decision on delivering S-300 to Iran has been taken, but the realization of the project will take some time."

Moscow had suspended action on a 2010 contract with Tehran following intense lobbying by Israel, yet progress on talks toward a nuclear agreement with Iran prompted Russian President Vladimir Putin last month to honor obligations under the estimated $800 million deal.