Russia marks Victory Day on Monday, commemorating the 77th anniversary of the Soviet Union's defeat of Nazi Germany in World War Two. Analysts say Putin may use his speech to boost public support for the ongoing invasion of Ukraine.

Victory Day is said to be the most patriotic date on the Russian calendar. Celebrations and parades take place across Russia, starting in the Far East.

Putin will give an address during a ceremony, which is scheduled to begin at 10 a.m. at Red Square in central Moscow.

UK Defence Secretary Ben Wallace and others have said that Putin may declare war during the speech. They are suggesting that such a declaration may lead to a huge mobilization of Russians for the invasion.

Putin ordered the military to invade neighboring Ukraine in late February. He accused Ukrainian President Volodymyr Zelenskyy's administration of being overrun by neo-Nazis and claimed that people of Russian descent need to be protected.

Putin's speech will be followed by a military parade featuring a march of more than 10,000 personnel with state-of-the-art weapons on display.

The parade will also showcase the Ilyushin Il-80, a so-called "doomsday" special aircraft from which the president and other officials issue commands in case of emergencies, such as a nuclear war.

Experts say flying the plane will be aimed at evoking the image of nuclear conflict as a warning to Western nations that have been supplying military equipment to Ukraine.

Some reports suggest that Russia may also hold ceremonies in Ukrainian areas that it claims to have captured during the invasion.