President Vladimir Putin on Monday lifted a ban on supplying Iran with sophisticated S-300 air defense missile systems, the Kremlin said, after Tehran struck a deal with the West over its nuclear program.

Israeli officials responded with dismay to the report, saying the supply, if it goes ahead, would change the balance of power in the region. 

Israeli officials said supply of the system to Iran could prevent any military strike on Iran’s nuclear facilities, Channel 2 news reported. The TV report also cited unnamed American officials responding with concern to the news.

A decree signed by Putin removes a ban on “the shipment from Russia to Iran” of the S-300 missiles, the Kremlin said in a statement.

Russia signed a 2007 contract to sell Tehran the S-300 system, but the weaponry was never delivered amid strong objections by the United States and Israel.

Moscow blocked deliveries of the surface-to-air missiles to Tehran in 2010 after the United Nations slapped sanctions on Iran over its nuclear program barring hi-tech weapons sales.

Iran then filed a $4 billion suit against Moscow at an arbitration court in Geneva.

The decision to lift the delivery freeze comes after Tehran and international powers including Russia made a major breakthrough this month by agreeing an outline deal aimed at curbing Iran’s nuclear program.

The Lausanne framework marked a crucial advance in a 12-year standoff between Iran and the West, which disputes Tehran’s denial that it is seeking to build a nuclear bomb. However, Israeli officials, led by Prime Minister Benjamin Netanyahu, have strongly condemned the deal for placing inadequate limitations on Iran’s ability to research and produce nuclear weapons.

Global powers must resolve a series of difficult technical issues by a June 30 deadline for a final deal, including the steps for lifting global sanctions imposed on Iran, and lingering questions over the possible military dimensions of its nuclear program.

Iran’s Supreme leader Ayatollah Ali Khamenei, who will have the final say on any deal, has plunged the accord into doubt suggesting that “nothing is binding” while President Hassan Rouhani demanded that sanctions be immediately lifted when any deal is signed.

Global powers Britain, China, France, Germany, Russia and the United States have said sanctions will only be gradually eased and want a mechanism to ensure they can be swiftly reimposed if Iran breaks its word.

Despite the dispute over the S-300 missiles, Moscow and Iran have remained on good terms, with Russia agreeing to build new nuclear reactors for Tehran and both sides supporting President Bashar al-Assad in Syria.

The S-300, developed by the Soviet Union in 1979, is a series of Russian long-range surface-to-air missile systems produced by NPO Almaz. The S-300 system was constructed for the Soviet Air Defense Forces in order to defend against aircraft and cruise missiles. Subsequent variations on the model were developed to intercept ballistic missiles.