The speaker of Russia’s lower house of parliament warned that Ukraine was dragging the United States and Europe into a major global war and on Thursday urged Western leaders to act responsibly to avoid a catastrophe.

President Vladimir Putin’s war in Ukraine has touched off the worst breakdown in relations between Russia and the West since the 1962 Cuban Missile Crisis. Russia is now advancing along the front line in Ukraine.

“The Kyiv regime is dragging the United States and European countries into a big war,” said Vyacheslav Volodin, the speaker of the State Duma, who is a close ally of Putin’s and a member of Russia’s Security Council.

He said that Ukrainian lawmakers were trying to convince the United States to allow Kyiv to use U.S.-supplied weapons to strike Russian territory.

“This path leads to a tragedy that can affect all of humanity,” Volodin said. “Western politicians need to realise their responsibility and do everything to avoid bringing the situation to a global catastrophe.”

In Kyiv on Wednesday, U.S. Secretary of State Antony Blinken said that Washington had “not encouraged or enabled strikes outside of Ukraine, but ultimately Ukraine has to make decisions for itself about how it’s going to conduct this war.”

“We’ve been clear about our own policy, but again, these are decisions that Ukraine has to make, Ukraine will make for itself,” Blinken said, according to a transcript of his remarks provided by the U.S. State Department.

Ukraine says it has the right to attack Russian targets as it is being struck by Russian missiles on a daily basis. The United States has been wary of its weapons being used in a direct attack on Russia, the world’s biggest nuclear power, due to the wider risks.

Putin and U.S. President Joe Biden have cautioned that a direct confrontation between Russia and the U.S.-led NATO military alliance could trigger World War Three.

Russia has warned that the use of U.S. and Western weapons against targets inside Russia could trigger a new level of confrontation – and Putin has ordered tactical nuclear weapon exercises, partly as a response to Western statements.

“Any use of American and European weapons to attack peaceful cities of the Russian Federation will require the use of more powerful weapons to protect the citizens of our country,” Volodin said.

Putin accused the West last week of risking a global conflict and said no one would be allowed to threaten Russia.