JERUSALEM (JTA) — Israeli Prime Minister Benjamin Netanyahu said Israel views with “upmost gravity” Russian President Vladimir Putin’s decision to sell advanced surface-to-air missiles to Iran.

“Israel views with utmost gravity the supply of S-300 missiles from Russia to Iran, especially at a time when Iran is stepping up its aggression in the region and around the borders of the State of Israel,” Netanyahu said Sunday at the beginning of the weekly Cabinet meeting.

Iran reportedly has said Russia could deliver the missile systems to the Islamic Republic this year.

“Every year the missiles are bigger and enhanced – in accuracy, strength and deadliness; however, one thing does not change. What does not change is the inscription ‘Death to Israel’ on the missiles. Against the threats that I have described, Israel will do whatever is necessary to defend the security of the state and its citizens,” Netanyahu said.

He reportedly called Putin last week to protest the sale.

“Vladimir Putin explained the rationale for the decision in the current context and highlighted the fact that due to their tactical and technical characteristics, S-300 have a purely defensive significance and pose no threat to Israel,” the Kremlin said in a statement, according to Russian media reports.

Putin also reportedly said that Russia’s withholding of selling the weapons to Iran had been voluntary and not connected to international sanctions against Iran.

Meanwhile, Putin over the weekend warned Israel against selling arms to Ukraine, which Israel floated as a response to the Russian sale to Iran.

“It’s the Israeli leadership’s choice. It’s their right to do what they think is appropriate,” Putin told state-run media, according to reports. He called the proposed sale “counterproductive.”

” It will only lead to another round of conflicts, to a rise in the number of victims, and the outcome will be the same,” Putin reportedly said.