Chancellor Olaf Scholz is under pressure at home and abroad over arms sales to Ukraine, with Kyiv blasting its refusal to send main battle tanks that would reinforce Kiev’s counter-offensive against Russia.

On Tuesday, Ukrainian Foreign Minister Dmytro Kuleba criticized “disappointing signals from Germany” for further arms deliveries.

“Not a single reasonable argument as to why these weapons cannot be delivered, just abstract fears and excuses,” Kuleba said in a Twitter post.

“What is Berlin afraid of that Kyiv is not.”

After initially refusing to supply Kiev’s armed forces with deadly weapons when war broke out, Germany has since increased its arms supplies to Ukraine.

Mounds of ammunition and rocket launchers were sent to Ukraine from gunsmiths and the Bundeswehr’s own warehouses, as were dozens of tanks and howitzers.

Kuleba’s angry letter sparked a new debate over Germany’s apparent reluctance to do more to help Kyiv in its efforts to repel the Russian invasion.

But Berlin has so far refused to send the coveted Leopard main battle tanks, and Chancellor Olaf Scholz said Monday Germany will not “go it alone” on arms deliveries without coordinating with allies.

Ukrainian forces have used weapons supplied by Western allies to great effect in their counter-offensive launched in early September as they regained control of large swaths of the north-east and south of the country.

Germany has “delivered very efficient weapons that are making the difference on the battlefield at the moment,” Scholz argued on Monday.

German Defense Minister Christine Lambrecht separately stressed that “no country” had sent western-made main battle tanks to Ukraine, reiterating that Berlin had agreed to coordinate with allies on arms supplies.

But the US embassy in Berlin said: “The decision about the type of aid ultimately lies with each country individually.”

“We call on all allies and partners to support Ukraine as much as possible in its struggle for democratic sovereignty,” the embassy wrote in a post on Twitter.

The decision not to send the weapons during Ukraine’s counter-offensive was “surprising and short-sighted,” senior Ukrainian presidential adviser Mykhaylo Podolyak told the German daily Bild.

German arms manufacturer Rheinmetall told public broadcaster ARD that 16 Marder infantry fighting vehicles, which it had restored at its own expense, are “ready for delivery” to Ukraine if officials in Berlin give the go-ahead.

In addition to the Leopard main battle tanks, the Marders are at the top of the list of deliveries to Berlin required by Ukraine.

Rheinmetall is preparing a further 14 Marders, with the potential to deliver a further 70 vehicles from the warehouse, ARD reported.

The heated debate over the leopards and martens recalled the earlier uproar over Germany’s initially spluttering response to providing military support to Kyiv.

The Scholz government only reversed itself after many public speeches by Ukrainian leaders, and the chancellor has since said Germany will take “special responsibility” to help Ukraine build up its artillery and air defense systems.

But Ukraine’s urgent requests for Leopard tanks and Marder vehicles have so far gone unanswered, and even representatives of the governing coalition of Scholz’s Social Democrats, FDP and Greens are urging the Chancellor to give in.

Berlin’s refusal to send the armament was “at the expense of Ukraine,” said the chair of the parliamentary defense committee, FDP MP Marie-Agnes Strack-Zimmermann, to the AFP news agency.

Germany should “stop hiding behind other countries,” said senior Green MP Anton Hofreiter to the media network RND.

“Sooner or later we will not be able to avoid supplying modern, Western main battle tanks to Ukraine,” he said.

Agreements with allies about arms deliveries are not “set in stone,” said the Social Democratic chairman of the Bundestag’s foreign affairs committee, Michael Roth, on Deutschlandfunk.