Putin, in Threat to West, Says Russia Struck Ukraine With New Missile

President Vladimir V. Putin escalated a tense showdown with the West on Thursday, saying that Russia had launched a new intermediate-range ballistic missile at Ukraine in response to Ukraine’s recent use of American and British weapons to strike deeper into Russia.

Mr. Putin called the strike a “test” of a new missile called the Oreshnik and said that it was successful, hitting a military-industrial complex. Ukraine said that a volley of missiles, including the intermediate missile, targeted the eastern city of Dnipro on Thursday, the latest assault in a week of rising hostilities between the two adversaries.

In what appeared to be an ominous threat against Ukraine’s western allies, Mr. Putin said: “We consider ourselves entitled to use our weapons against the military facilities of those countries that allow their weapons to be used against our facilities.”

In the last few days, the Ukrainian military has used longer-range American and British missiles to strike into Russia, after the two countries granted permission to do so after months of Ukrainian requests. In response, Mr. Putin lowered the threshold for Russia’s use of nuclear weapons.

Mr. Putin said Russia was still ready “to resolve all contentious issues by peaceful means. But we are also ready for any development. If anyone still doubts this, it is in vain. There will always be a response.”

Mr. Putin made his comments in a rare address to the nation. His tone was both boastful and threatening, saying he was sending his message to “the Russian Armed Forces, the citizens of our country, our friends around the world, as well as those who continue to harbor illusions about the possibility of inflicting a strategic defeat on Russia.”

The use on Thursday of a missile drawn from Russia’s strategic arsenal was notable, Ukrainian and Western officials said. The target inside Ukraine was well within the range of the conventional weapons that Moscow has routinely used throughout the war.

Instead, Russia launched a longer-range missile capable of carrying nuclear warheads that is mainly intended as nuclear deterrence; that choice, the officials said, signals a warning aimed at striking fear into Kyiv and its allies.

Ukraine did not contend that the powerful missile carried nuclear weapons.

President Volodymyr Zelensky of Ukraine said, “Putin is using Ukraine as a testing ground.” He added: “Obviously, Putin is terrified when normal life simply exists next to him.”

Karine Jean-Pierre, the White House press secretary, told reporters on Thursday that “the escalation at every turn, at every step, is coming from Russia.”

She repeated the White House’s position that the decision to bring North Korean troops into the conflict was the important escalatory action, and that changes in policy about U.S. weapons were not. “This is their aggression: not Ukraine’s, not ours,” she said.

Although other Russian missiles that have been launched into Ukraine can also carry nuclear weapons — like the Iskander and the Kh-101 — what makes an intermediate range missile more alarming is its ability to fire multiple nuclear warheads when it re-enters the earth’s atmosphere, said Tom Karako, director of the missile defense project at the Center for Strategic and International Studies in Washington. That makes it difficult, if not near impossible, to intercept them.

The missiles are also large and can fly far and fast, at some points reaching hypersonic speed. It represents “a nuclear saber-rattling for both Ukraine and Europe itself,” Mr. Karako said. “It’s a pretty sharp signal.”

In a statement on Wednesday, the United States National Security Council said that Russia launched what it called “an experimental intermediate-range ballistic missile against Ukraine.” The statement said Russia likely had “only a handful” of these missiles and had likely used it to try to “intimidate Ukraine and its supporters.”

Roman Kostenko, the chairman of the defense and intelligence committee in Ukraine’s Parliament, said that Thursday’s attack would not prompt Ukraine to alter how it is fighting the war, including striking back at targets in Russia in self-defense.

But Ukraine halted its nuclear missile production after gaining independence in 1991, and now, Col. Kostenko said, “we have nothing to answer to this class of weapons.”

Ukraine is struggling to hold off fierce Russian advances that have captured territory at an accelerated pace in Ukraine’s east.

Michael Schwirtz, Maria Varenikova, Nataliia Novosolova, Liubov Sholudko and Zach Montague contributed reporting.