In August, two high-ranking military officials expressed concern that the S-400 was being tested with older interceptors from the S-300P system and concluded that it was not ready for deployment.

[10] Russia had accepted for service the 40N6 long-range missile for the S-400 air-defence system, a source in the domestic defense industry told TASS news agency in October 2018.

[23] The Moscow-1 passive sensor is 2+1⁄2 times more effective than the Protivnik, with a 400-kilometre (250 mi) range[24] Orion[25] for a target-designation on-the-air defense system, and the Avtobaza-M[26] and Orion+ Avtobaza add high-precision detection.

The 96L6E2 export version can track a maximum of 20 targets,[better source needed] and is resistant to false returns of clutter in mountainous terrain.

[87] In September 2006 Deputy Prime Minister Sergei Ivanov announced the purchase of 18 S-400 battalions for internal defense for the period 2007–2015.

On 22 May 2018 Israeli Air Force commander Major General Amikam Norkin reported that Israel became the first country in the world to use the F-35I Adir in combat during recent clashes with Iran in Syria.

[103] In late December 2021, the Israeli Air Force flew military jets over areas protected by S-400 and Pantsir SAM in Syria and bombed Iran-backed Hezbollah militia based in Latakia.

[77] On 16 October 2023, units from the Ukrainian Special Operations Forces carried out precision strikes targeting two key Russian airbases in Berdiansk and Luhansk destroying S-400 surface-to-air missiles.

On 23 August 2023, GRU released a video of two alleged elements of an S-400 battery being destroyed in Olenivka, Crimea, 120 km (75 mi) south of Kherson, by a barrage of Ukrainian missiles.

In late October 2023, Russian sources claimed that the S-400 was used in conjunction with the Beriev A-50 flying radar to shoot at Ukrainian air targets with new warheads of anti-aircraft guided missiles.

[117][118] On 19 April 2024, Ukraine launched ATACMS missiles at Russian military airfield in Crimea and destroyed Russia's S-400 launchers, three radars and Fundament-M air surveillance system.

[120] On 6 May 2024, Ukrainian forces reportedly destroyed a tracked version of Russian S-400 missile launcher in the occupied Zaporizhzhia region.

[121] On 23 May 2024, Ukrainian forces launched multiple ATACMS missiles at Russian position in Donetsk region destroying 96L6 radar and at least two of the launchers.

[121] On 30 May 2024, the Security Service of Ukraine (SBU) destroyed a Russian Nebo-SVU long-range VHF surveillance radar system in Crimea.

In one such attack on 13 December 2023 out of 10 missiles fired at Kyiv, all were supposedly downed, but falling debris still caused some damage in residential regions.

[124][125] On 3 June 2024, Ukrainian forces destroyed for the first time an S-400 air defence missile system in Belgorod using a U.S.-supplied M142 HIMARS rocket launcher.

Army Recognition published photos of a destroyed 5P85SM2-01 transporter erector launcher[126] and power generation unit from the S-400 system.

[136] On 1 December 2021 Belarus President Alexander Lukashenko, in response to a reporter's question, replied that a Belarusian training center already has S-400 systems.

[139] On 13 April 2015, the chief executive of the Russian state-run arms trader Rosoboronexport confirmed that China secured a contract for the purchase of the S-400 air defense system.

[146][147] The US Secretary of State raised concerns over the deal,[148] which were rebuffed by President Erdogan and other Turkish officials, citing the US refusal to sell the upgraded MIM-104 Patriot to Turkey, considered to be an important American ally by the US.

[157][158] On 26 September 2018, the Cabinet Committee on Security (CCS), headed by the Prime Minister Narendra Modi further cleared the acquisition.

[162] The first squadron of S-400 was received by India in December 2021 and deployed in the along the Line of Control (LoC) Pathankot region to protect Punjab-Jammu & Kashmir sector.

[169] Delivery of the remaining two systems are likely to be dependent on the resolution of issues such as insurance and establishment of mechanism for balance payments which are delayed due to sanctions on Russia following the 2022 Russian Invasion of Ukraine.

[178] Saudi Arabia is no longer considering the Russian S-400 air defense system, following the kingdom's deal for an American alternative.

[179] In June 2019 some Iranian officials expressed interest in procuring the S-400 missile system to further improve its defense capabilities along with the previously purchased S-300PMU2.

[181] In February 2018 Iraqi Minister of Foreign Affairs Ibrahim al-Jaafari confirmed ongoing rumors that his country had shown interest in the S-400 and that negotiations with Russia were underway.

[182][183][184] In May 2019 Iraq's ambassador to Russia, Haidar Mandour Hadi, said the Iraqi government had decided to procure the S-400 air defense system.

[185] In June 2020 United States senator John Thune proposed an amendment to the (ultimately unsuccessful) Senate version of the 2021 National Defense Authorization Act to allow the US Department of Defense to purchase Turkey's S-400 system with funds from the U.S. Army's missile procurement account,[186] thus negating Turkey's contravention of the CAATSA sanctions.

[188][189] South Korea is developing the KM-SAM, a medium-range SAM system based on technology from the 9M96 missile, with assistance from NPO Almaz.

The prime contractor is Hanwha Group (formerly Samsung-Thales, a defunct joint venture between South Korea's Samsung and France's Thales).