MOSCOW (AP) — Russian President Vladimir Putin said Wednesday that a U.S. reconnaissance aircraft was operating in sync with a British destroyer during last week’s Black Sea incident in what he described as a “provocation" to test Moscow's response.

Moscow said one of its warships fired warning shots and a warplane dropped bombs in the path of British destroyer Defender on June 23 to force it out of an area near the Crimean Peninsula, which Russia annexed in 2014. Britain denied that account, insisted its ship wasn’t fired upon and said it was sailing in Ukrainian waters.

Asked if the incident could have triggered World War III, Putin said that it was hardly possible even if Russia had sunk the British warship because Western powers knew they couldn't emerge as winners in a global conflict.

Speaking during a live call-in show, Putin said that the U.S. aircraft’s apparent mission was to monitor the Russian military’s response to the British destroyer. He added that Moscow was aware of the U.S. intentions and responded accordingly to avoid revealing sensitive data.

In Wednesday’s incident, Britain insisted the Defender had been making a routine journey through an internationally recognized travel lane and remained in Ukrainian waters near Crimea. The U.K., like most of the world, recognizes Crimea as part of Ukraine despite the peninsula’s 2014 annexation by Russia.

Russia denounced the Defender’s move as a provocation and warned that next time it could fire to hit intruding warships if they again try to test Russian military resolve.

Responding to a question about Russia’s tug-of-war with Ukraine, Putin emphasized his long-held claim of close kinship between the Russian and Ukrainian peoples, but accused the Ukrainian leadership of maintaining a hostile course toward Russia.

The Russian president spent most of the marathon call-in show speaking on domestic issues.

He voiced hope that the country could avoid a nationwide lockdown amid a surge of new infections. Putin argued that decisions by local authorities in a number of regions who made vaccination mandatory for some workers should help contain the new wave of infections and avoid a lockdown.

The “actions of our colleagues in certain regions are aimed at avoiding the need for a lockdown, when entire enterprises shut down and people are left without their jobs, without their salaries,” Putin said.

He also revealed that he chose Sputnik V — the domestically developed coronavirus vaccine Russia hailed as the first in the world to be authorized for use — for his vaccination. Putin got his first coronavirus shot in late March out of the public eye, and has remained tight-lipped about which vaccine out of three domestically developed ones available at the time he chose.

The Russian president said he wasn’t consulting with his doctors about this, but rather looked at choices his acquaintances made, and went for Sputnik V, as it provided the longest protection against the virus. He added that he initially didn’t name the vaccine he took to avoid offering an advantage to its maker

Russia gave Spuntik V regulatory approval last August and faced criticism both at home and abroad, as the shot had only been tested on a few dozen people at the time. However, the criticism has been blunted by a report in the prestigious British medical journal The Lancet this year that said large-scale testing showed it to be safe, with an efficacy rate of 91% against the virus.

Russia has struggled to cope with a surge in infections and deaths in recent weeks that comes amid rather slow vaccination rates. Coronavirus deaths in Russia hit a new daily record Wednesday, with the authorities reporting 669 new deaths.

Russia has been registering over 20,000 new coronavirus cases and around 600 deaths every day since last Thursday. On Wednesday, 21,042 new infections were recorded.

Russian officials have blamed the surge, which started in early June, on Russians’ lax attitude toward taking necessary precautions, the growing prevalence of more infectious variants and low vaccine uptake, which experts attribute to widespread vaccine hesitancy and limited production capacity. Although Russia was among the first countries to announce and deploy a coronavirus vaccine, just over 15% of the population has received at least one shot.

Russia’s coronavirus task force has reported more than 5.5 million confirmed coronavirus cases in the pandemic and 135,214 deaths.

Amid the surge, about 20 Russian regions — from Moscow and St. Petersburg to the remote far-eastern region of Sakhalin — have made vaccinations mandatory this month for employees in certain sectors, such as government offices, retail, health care, education, restaurants and other services. The move has helped speed up the pace of vaccinations.

While reaffirming his position that vaccination should be voluntary, Putin emphasized that the decisions by local authorities were based on law and necessary to prevent tougher measures.

Putin noted that some people still get infected with COVID-19 even after being immunized, but emphasized that the disease takes a milder course.

Along with his annual marathon news conference, carefully choreographed call-in shows are intended to cast Putin as a strong leader caring about people’s daily needs and attentive to their problems. Most of the questions asked related to the pandemic, social payments, rising consumer prices and other domestic issues. Overall, more than 2 million questions were sent to the show’s hotline.