The US defence secretary, Lloyd J. Austin III, opened a meeting of western defence officials on Friday to coordinate additional military assistance for Ukraine, even as the critical question of whether European tank deliveries to Kyiv would be authorised remained unanswered.

Despite mounting pressure from many European allies, it was still unclear whether Berlin would send some of its Leopard 2 tanks to Ukraine or allow other European nations to send their own supplies of the German-made vehicle to the fight.

In the lead-up to the meeting, a gathering of the Ukraine Defence Contact Group at Ramstein Air Base, Kyiv’s allies promised significant supplies of weapons to the front line. Flanked by Ukraine’s defence minister, Oleksii Reznikov, and Mark A. Milley, the chairman of the Joint Chiefs of Staff, Austin reiterated on Friday that the US would support Ukraine for “as long as it takes”.

“Russia is regrouping, recruiting and trying to reequip. This is not a moment to slow down — it’s a time to dig deeper,” Austin said. “The Ukrainian people are watching us, the Kremlin is watching us, and history is watching us,” he added.

The meeting, which includes officials from as many as 50 countries, is focused on how to provide weapons to Ukraine to try to push back Russian troops from occupied territory in eastern Ukraine.

Austin went through the list of new promises of armoured vehicles and air defence systems, most notably the US-made Patriot missiles. But absent from that list was the weapon Ukraine and some of its allies have argued in recent weeks is most urgently needed: tanks.

Ukraine has asked for both the US-made Abrams and Germany’s Leopard 2 tank, of which 2,000 are available across Europe. The Leopard is widely seen as the best option, given that it is already on the continent and many European allies have spare parts.

There have been suggestions that Berlin does not want to send any of its own Leopards unless the US agrees to also send its M1 Abrams tanks, which the Biden administration has been reluctant to do.

New York Times News Service