President Putin, after extending his rule in an election that stifled opposition, is vowing that Moscow will not relent in its invasion of Ukraine and plans to create a buffer zone to help protect against long-range Ukrainian strikes and cross-border raids.

The Kremlin’s forces have made battlefield progress as Kyiv’s troops struggle with a severe shortage of artillery shells and exhausted front-line units after more than two years of war. The front line stretches over 620 miles across eastern and southern Ukraine.

Advances have been slow and costly, and Ukraine has increasingly used its long-range firepower to hit oil refineries and depots deep inside Russia. Also, groups claiming to be Ukraine-based Russian opponents of the Kremlin have launched cross-border incursions.

“We will be forced at some point, when we consider it necessary, to create a certain ‘sanitary zone’ on the territories controlled” by Ukraine, Mr. Putin said late Sunday.

This “security zone,” Mr. Putin said, “would be quite difficult to penetrate using the foreign-made strike assets at the enemy’s disposal.”

He spoke after the release of election returns that showed him securing a fifth six-year term in a landslide in an election devoid of any real opposition following his relentless crackdown on dissent.

The Central Election Commission said Mr. Putin received some 87 percent of the vote, the highest number for any president in post-Soviet Russia. It said turnout was 77 percent of the electorate, also the biggest. Others on the ballot all finished in single digits, and anti-war candidates were not allowed to run.

The state news agency RIA Novosti said the vote “as expected … took place in an atmosphere of unprecedented national unity.”

There was no video from CCTV cameras at polling stations depicting voter fraud or ballot-box stuffing, as access to the footage was more heavily restricted than in previous elections, and hardly any independent monitors were on hand to document irregularities.

There still was voter intimidation, however, according to Russia’s prominent independent election watchdog, Golos, noting it received reports of citizens being pressured to vote in over 60 Russian regions.

On Sunday, voters were searched at polling stations, and some reported police checking their ballots before they were cast or peering over their shoulder while they filled them out, Golos said.

“Nothing like that has happened on such a scale at elections in Russia before,” Golos said in a statement Monday. A total of 89 people were detained Sunday in 22 cities, said a rights group that monitors political arrests, OVD-Info.

The 71-year-old Russia leader “chose to show his adversaries his power,” said political analyst Abbas Gallyamov, a former Putin speechwriter.

Monday marks the 10th anniversary of Russia’s seizure of Ukraine’s Crimea Peninsula, which set the stage for Russia to invade its neighbor in February 2022. However, Mr. Putin has been vague about his goals in Ukraine since that full-scale invasion floundered.

Mr. Putin again warned the West against deploying troops to Ukraine. A possible conflict between Russia and NATO would put the world “a step away” from World War III, he said.

Commenting on the prospects for peace talks with Kyiv, Mr. Putin reaffirmed that Russia remains open to negotiations but won’t be lured into a truce that will allow Ukraine to rearm.

However, President Zelensky has apparently shut the door on such talks, saying Mr. Putin should be brought to trial at the International Criminal Court in The Hague, which last year issued an arrest warrant for the Russian tyrant on war crime charges.

With American aid being held up by right-wing Republicans in Congress, Senator Graham arrived at Kyiv on Monday, the American Embassy said. Ukraine desperately needs the around $48 billion that the package of support would provide, especially artillery shells and air defense systems.