Washington (CNN) US officials dismissed President Vladimir Putin's boast of resurgent Russian military might as "cheesy" and made clear that US defense and military capabilities remain "second to none."

In a speech on Thursday Putin said that Moscow has developed new drones as well as nuclear weapons systems with an "unlimited" range that will render NATO defenses "completely useless." The missiles, he said, are "invincible" and can deliver a warhead at hypersonic speed.

Putin interspersed his address to Russia's Federal Assembly with video clips showing nuclear warheads pummeling Florida, the site of President Donald Trump's Mar-a-lago estate.

Dismissing it as a "cheesy video," State Department spokeswoman Heather Nauert said, "we don't think it's responsible." Pentagon officials said that Americans should rest assured that "we are fully prepared," even as experts cast doubt on the truth of Putin's claims.

White House spokeswoman Sarah Sanders said, "President Putin has confirmed what the United States government has known all along, which Russia has denied. Russia has been developing destabilizing weapons systems for over a decade, in direct violation of its treaty obligations."

And she engaged in some American chest thumping.

"Second to none"

"US defense capabilities are and will remain second to none, and now because of the new defense budget of 700 billion dollars, our military will be far stronger than ever," Sanders said. "As the president's nuclear posture review made clear, America is moving forward to modernize our nuclear arsenal and ensure our capabilities are unmatched."

Putin's claims reflect growing tensions over US changes to its defense and nuclear postures, as well as Washington's response to Moscow's annexation of Crimea. The Trump administration declared Russia a rising threat in its national security blueprint, boosted its military presence in Eastern Europe, and announced plans to modernize its nuclear arsenal

"I see some of this as a response to the US nuclear posture review, which is quite remarkable in that it stresses the importance of nuclear weapons and building up the US nuclear arsenal -- something President Trump himself has said," said Angela Stent, director of Georgetown University's Center for Eurasian, Russian and East European Studies.

The Pentagon on Thursday said it was "not surprised" by Putin's claim that Russia could strike anywhere in the US. "We're not surprised by the statement. And the American people should rest assured that we are fully prepared," chief Pentagon spokesperson Dana White said.

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White said the US missile defense systems are not about Russia; US officials have long stressed that these systems are more about countries like Iran. "They know very well that it's not about them. Our missile defense has never been about them," White said, referring to US nuclear deterrence policy. "We need to ensure we have a credible nuclear deterrent, and we are confident that we are prepared to do -- and we are prepared to defend this nation no matter what."

It's not clear how viable Russia's new weapons systems are either. A US official with knowledge of the latest Russian military information tells CNN that the US has observed a small number of Russian tests of its nuclear-powered cruise missile and seen them all crash.

The official says they observed less than a "handful" of tests. They emphasized strongly that there is considerable doubt that the systems Putin described Thursday are anywhere near operational. The US military doesn't defend against Russia, the official pointed out.

Campaign season

But the Russian President's bravado about his military also comes less than a month before Russian presidential election s and strike many analysts as a campaign gambit, along with promises to increase pensions, pull more people out of poverty, and enact more democratic reforms.

"He's basically telling the Russian population 'we are invulnerable now,' " Stent said. The message to the outside world is "don't mess with us, we are a major nuclear power."

Stent notes that Putin's address to the upper and lower houses of Russia's parliament was originally scheduled for December and was rescheduled just before Russians go to the polls for a vote whose outcome is in little doubt.

In his remarks, Putin pointed to the US as the problem, saying that the US position "reduces the threshold for the use of nuclear weapons," and pointing out that Washington has unilaterally walked away from arms control treaties with Moscow in the past.