US and Russian defense chiefs spoke on Friday for the first time in months, but Secretary of State Antony Blinken said he saw no interest from Moscow in broader talks to end the Ukraine war.

Defense Secretary Lloyd Austin “stressed the importance of maintaining lines of communication amid the ongoing war against Ukraine” while meeting with his Russian counterpart Sergei Shoigu, a US spokesman, Brigadier General Pat Ryder, said.

The Russian Defense Ministry confirmed the call and said the two had spoken about Ukraine without further details.

Defense chiefs last spoke on May 13, when Austin called on Moscow to institute an “immediate ceasefire” in Ukraine.

Russia has not done so, and Kiev’s forces have since retaken parts of territory from Moscow’s forces in the east and south of the country, with billions of dollars worth of weapons sent by the United States and other Western powers.

Austin spoke separately with his Ukrainian counterpart Oleksiy Reznikov “to reaffirm the US’s unwavering commitment to supporting Ukraine’s ability to counter Russian aggression,” Ryder said.

Blinken said the United States would maintain contact with Russia, but said any broader diplomacy would depend on President Vladimir Putin showing an interest in “stopping the aggression.”

“We haven’t seen any evidence of that at the moment. On the contrary, we see Russia doubling and tripling its aggression,” Blinken said at a joint press conference with French Foreign Minister Catherine Colonna.

Blinken pointed to Russia’s recent attacks on power plants and other civilian infrastructure in Ukraine and the mobilization of troops, which Blinken called “terrible cannon fodder that Putin is trying to throw into the war.”

“The fundamental difference is that Ukrainians are fighting for their country, their country, their future. Russia doesn’t, and the sooner President Putin understands that and comes to that conclusion, the sooner we’ll be able to end this war,” Blinken said.

Blinken met with Russian Foreign Minister Sergei Lavrov in January to warn of the consequences of an invasion Moscow carried out a month later. Blinken has since refused to see Lavrov but spoke to him by phone in July to free Americans detained in Russia.

Russia’s Ambassador to the United States, Anatoly Antonov, recently complained that the two nuclear powers lack a backchannel like the one used this month during the Cuban Missile Crisis 60 years ago.

The then Soviet ambassador secretly met with Robert F. Kennedy, the President’s brother and Attorney General, to exchange high-level messages.

“Attempts by Russian diplomats in Washington to reestablish such contacts have been in vain,” Antonov told Newsweek.

President Joe Biden’s administration “is not ready to speak to us as equals,” he said.

Biden and Putin have both downplayed the chance they would speak on the sidelines of a G20 summit in Bali next month.

One Western leader who has hired Putin is French President Emmanuel Macron, who also tried unsuccessfully to prevent war from breaking out.

Macron’s involvement has unnerved some Eastern European nations wary of Russia, although France insists it has coordinated its diplomacy with allies.

Colonna, who spoke to Blinken at a think tank ahead of her talks, acknowledged limited success with Putin but said it was important to try.

“We believe it is absolutely crucial to maintain a channel of communication with decision-makers in Russia, including President Putin,” said Colonna of the Center for Strategic and International Studies.

“Putin is probably isolated in his very strange vision of the world and the way it might be governed. Reinforcing that isolation from him wouldn’t be a good option,” she said.

Macron’s talks with Putin helped secure a UN nuclear watchdog mission to travel to the Russian-occupied Zaporizhia nuclear power plant in Ukraine.