Vladimir Putin authorized a partial mobilization of Russian reservists on Wednesday, seven months after invading Ukraine.

It is Russia’s first mobilization since World War II, and Western Ukraine backers call it feeble, The Christian Science Monitor reported. Many Russians bought plane tickets, trying to leave the country.

In a seven-minute broadcast address to the nation on Wednesday, the Russian leader warned the West he would not bluff about protecting Russia’s territory. Putin urged the West not to support Ukraine and blasted NATO for arming the territory.

Putin accused the West and its allies of engaging in “nuclear blackmail” in his address, which was far shorter than previous speeches about the Ukraine war.

In the televised address on Wednesday, he noted statements by some high-ranking representatives of the leading NATO states about the possibility of using nuclear weapons of mass destruction against Russia, though he did not name any names.

“To those who allow themselves such statements regarding Russia,” he said, “I want to remind you that our country also has various means of destruction, and for separate components and more modern than those of NATO countries.”

The Russian president warned, “When the territorial integrity of our country is threatened, to protect Russia and our people, we will certainly use all the means at our disposal.”

“It’s not a bluff,” Putin added.

Russian officials could call up 300,000 reservists, according to The Hill. Even incomplete mobilization could make Russians mistrust the Ukraine war. Russian media reported a spike in demand for pricey international plane tickets after Putin’s address.

Only those with combat experience will be mobilized, stated Russian Defense Minister Sergei Shoigu. He said only 1% of the 25 million who qualify would be activated. Most professional soldiers cannot leave until partial mobilization is lifted.

Bridget Brink, the U.S. ambassador to Ukraine, said the mobilization shows the Ukraine invasion has been a failure for the Russians.

“Sham referenda and mobilization are signs of weakness, of Russian failure,” she tweeted. “The United States will never recognize Russia’s claim to purportedly annexed Ukrainian territory, and we will continue to stand with Ukraine for as long as it takes.”

On September 16, Ukraine president Volodymyr Zelenskyy called Russia a “terrorist country.”

“I don’t know why the world is slow to recognize it,” he tweeted. “We liberated Izium. Over 400 graves were found in the forest next to it. How many tortured Ukrainians are there is unknown. How many more of our people must die so that all finally figured it out?”

Zelenskyy will address world leaders at the UN General Assembly via video on September 21, one day after Russia announced the mobilization, the New York Post reported.

Zelenskyy’s spokesman called the mobilization “a big tragedy.”

This month’s Ukrainian counteroffensive seized Russian-held territory, and Russian forces fled rapidly, abandoning tanks and other weapons, The Dallas Express reported.

Defense Minister Shoigu said 5,937 Russian soldiers died in Ukraine, less than Western estimates of tens of thousands.

The directive came a day after Russian-controlled territories in eastern and southern Ukraine proclaimed preparations for joining Russia.

The war has escalated worldwide food and energy prices and raised fears of a nuclear tragedy in Russia-occupied southeast Ukraine.