“NATO is a defense alliance, but it is also a nuclear alliance,” said Geoana, who is also a former Romanian foreign minister and ambassador to the United States. “If they use chemical weapons or other high-tech systems against Ukraine, it will radically change the nature of the war that Mr Putin has waged against Ukraine.” “I can guarantee that NATO is ready to respond proportionately,” Geoana added. Geoana did not specify to the AP what those actions might be, but his comments came as Russian officials declined to say whether Russia would use chemical or nuclear weapons in its invasion. Russia has become more desperate as the war continues for more than a month, with Russian forces previously believing they would occupy Ukraine within days. “Mr. Putin probably believed in his own post-imperial fantasies, thinking that the Ukrainians would welcome them with open arms,” Geoana said. “They are still coming to Ukraine. Russia does not have the forces and the ability to occupy the whole of Ukraine.” Shortly after Russia’s invasion of Ukraine on February 24, the international community retaliated with harsh sanctions and private companies withdrew from Russia. Geoana said Russian President Vladimir PutinVladimir Vladimirovich PutinPentagon: Russia loses part of control of first Ukrainian city to occupy Ukraine, Taiwan, Korea: Is the world heading for major wars? The Russian ambassador filed a lawsuit against the Italian newspaper for an article alleging that Putin’s death did NOT take into account “the bravery of the Ukrainian army” and the “unity of the political West” when he decided to start this war, according to the AP. NATO estimates that more than 40,000 Russian soldiers have been killed, wounded or captured since the invasion began. “We see that at the moment, Russian military planning is trying to reassess the situation – to try to compensate for the huge losses in people and material suffered in the first month of the war,” Geoana said. NATO countries provide humanitarian and military assistance to Ukraine, but have refrained from implementing a no-fly zone or supplying fighter jets, as the alliance considers these moves to involve the countries very directly in the fighting.