Bordering Lithuania and Poland that have firmly backed Ukraine in the conflict with Moscow, the heavily militarised region on the coast of the Baltic Sea does not share a land border with Russia.

As part of his visit, Putin met with Kaliningrad school students to mark the start of the school year, answering questions on topics ranging from the economy, space exploration and Moscow's military intervention in Ukraine.

"The mission of our soldiers... is to stop this war, protect the people and, of course, protect Russia itself," Putin said in televised remarks.

He also said that "Ukraine has started creating an anti-Russian enclave that threatens our country".

Putin's visit to Kaliningrad comes amid soaring tensions between Moscow and Brussels after the EU slapped Russia with several rounds of sanctions over its campaign in Ukraine.

Russia in June clashed with Lithuania after Vilnius banned the rail transit of sanctioned goods from mainland Russia to Kaliningrad.

Following threats and protest from Moscow, the EU said Lithuania must allow Russian goods to transit with the exception of weapons.

Last month, Russia said it deployed three aircraft carrying Kinzhal hypersonic missiles to Kaliningrad for "round-the-clock" duty.

Seized by the Red Army from Germany in the closing stages of World War II, Kaliningrad was separated from the Russian mainland following the break-up of the Soviet Union when Lithuania became an independent state.