The German chancellor has ruled out sending fighter jets to Ukraine, just days after committing to supplying tanks.
In an interview with a German newspaper, Olaf Scholz warned against a bidding war for weapons.
But Ukraine has asked allied nations to create a "fighter jet coalition" to bolster their capabilities.
The US said it would discuss the idea of supplying jets "very carefully" with Kyiv on Thursday.
In an interview with Tagesspiegel, Mr Scholz said his focus was on the delivery of German-made Leopard 2 tanks.
"The fact we've only just made a decision [on sending tanks] and the next debate is firing up in Germany, that just seems frivolous", he said.
On Wednesday Germany committed to supplying 14 of its Leopard 2 tanks to Ukraine, after weeks of pressure from allies.
Following Germany's commitment to send the tanks, the US said it would provide Ukraine with its M1 Abrams tanks.