Ukrainian special forces reported on Tuesday that they had struck two Russian military airfields, following the first-time deployment of long-range ballistic missiles supplied by the US. The details of the weapons’ delivery has been shrouded in secrecy – unlike previous aid provided to Ukraine from the Biden Administration. The missiles – which Ukraine has reportedly been petitioning the US to deliver for months – may prove key to helping Ukrainian forces in the months of conflict ahead. Here’s what we know. What are ATACMS and why does Ukraine need them? The Army Tactical Missile System (ATACMS) is a long-range guided missile that gives operational commanders the “immediate firepower to win the deep battle”. Produced by US global security and aerospace company Lockheed Martin, the missiles carry a 500lb (227kg) class blast fragmentation warhead. The weapons are fitted with a specialised GPS system and have a maximum range of 300km (around 190 miles) – though the ones supplied to Ukraine have a shorter range and carry cluster munitions. When fired, the clusters open in the air, releasing hundreds of bomblets rather than a single warhead. Ukraine says the missiles will help fuel their counteroffensive as it heads into the muddy and colder winter months, enabling troops to strike behind Russian lines while staying out of firing range. The ATACMS have been key in Ukraine’s ability to hit an airfield in Berdyansk since it is within striking distance of the shorter-range version of the missile, and the cluster munitions would be effective in hitting multiple targets. The closest Ukrainian troop positions on the western bank of the Dnieper River are just about 100 miles (160 kilometers) from Berdyansk. What have they been used for? On Tuesday, president Zelensky confirmed the ATACMS had been used on the battlefield against Russia and "executed very accurately” during an offensive known as “Operation Dragonfly”. Ukraine’s Special Operations Forces claimed that a nighttime attack on targets in eastern and southern Ukraine destroyed nine Russian helicopters and other military equipment and personnel at two airfields in Russia-occupied regions – including the one at Berdyansk. The missiles also struck an airfield in Luhansk, an occupied city in eastern Ukraine. The special forces also managed to successfully damage airfield runways, Ukraine said. “The ammunition depot in Berdyansk detonated until 4am. The detonation in Luhansk continued until 11am,” Ukrainian Special Operations Forces said in a statement. “Losses in the enemy’s manpower amount to dozens of dead and wounded. Bodies are still being pulled from the rubble.” How many ATACMS has the US provided? After many months of dragging its feet, the Biden administration greenlit the delivery of a “small number” of the missiles last month, following continued pressure from Ukraine. The delivery of the missiles was made quietly and US officials have refused to discuss it publicly. The expectation was that the first public acknowledgment would come when the missiles were used on the battlefield. An official who spoke to The Associated Press on condition of anonymity said the missiles got into Ukraine within the last few days. The US has refused to provide any details on how many missiles have been delivered, although officials had suggested that the plan was indeed to send a small number – roughly two dozen. During his Tuesday address, Mr Zelensky said: "Today I express special gratitude to the United States," adding that the missiles "have proven themselves." Why the secrecy? That intense secrecy is a marked change from previous US weapons sent by the Biden administration. In nearly all other cases, the US has publicly announced its decision prior to the weapons and equipment being shipped overseas. The hesitancy may be, in part, to do with the range of the missiles, with concerns that Kyiv could use the weapons to hit deep into Russian territory, enraging Moscow and escalating the conflict. Lingering US concerns about escalating tensions with Russia are reportedly the reason that the ATACMS version that went to Ukraine has a shorter range than the maximum distance the missiles can have. The small number of missiles sent also underscores the US reluctance to send the powerful weapons. Sending the cluster munition version will mark the second time the Democratic administration has moved to send that type of weapon. Read More Ukraine-Russia war – live: Putin’s forces suffer blow as helicopters destroyed by missile strikes, says Kyiv Experts reveal what the winter will bring for the Ukraine war – and why Putin will be banking on Trump