(Bloomberg) -- The Army is poised to send Ukraine some of its long-range ATACMS missiles armed with cluster munitions once President Joe Biden approves the transfer, according to the service’s top weapons buyer.

The service “has been postured for this eventuality for a while,” Army Assistant Secretary for Acquisition Doug Bush said in an interview. “We’re ready to go fast.”

US lawmakers have been calling for months for Biden to send ATACMS, or the Army Tactical Missile System, to Ukraine, and people familiar with the matter said last month that the president finally relented, telling Ukraine President Volodymyr Zelenskiy during his visit to Washington last month that he was willing to do so.

There are several versions of the missiles, including ones that carry cluster munitions or regular warheads. Cluster-armed ATACMS has a range of between 15-190 miles (25-300 kilometers). The weapons carry between 300 to 950 cluster munitions, according to the service’s official weapons handbook.

Bush said the missiles the US would ship have been identified. The ATACMS can be fired from the same launchers Ukraine already uses to fire GPS-guided missiles in batches of as many as six at a time. The difference is only one ATACMS is fired in a volley from the same launcher. 

Read More: US Set to Send Limited Number of ATACMS Missiles to Ukraine

The modifications needed to convert the launcher are “not that much, some cables, some software — it’s  not dramatic,” Bush said.

“We’re ready when and if the president decides to do this,” he said.

Bush declined to answer what percentage of the Army’s cluster-munition missiles might be sent to Ukraine, noting “certainly it’s a portion of it” but “I can’t say how much.” 

“We have not been making a cluster-munition version for a long time — so that’s an older inventory” but “it’s still being produced in limited numbers for foreign military sales today,” he said.

The Army is on track for initial deliveries soon of the first version of a longer-range ATACMS-replacement called the Precision Strike Missile that will allay some readiness concerns about providing ATACMS from Army inventory, Bush told reporters last month. Both are made by Lockheed Martin Corp.

(Updates with Bush quotes on munitions in eighth and ninth paragraphs)

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