Tens of thousands of anti-government protesters packed Minsk's streets on Sunday as the army waded into the Belarus political crisis.
Huge nationwide demonstrations that erupted after the country's disputed election on August 9 have provided the biggest challenge yet to veteran leader Alexander Lukashenko's 26-year-old rule and tested the loyalty of his security forces.
The streets of Minsk turned red and white as a flood of demonstrators carried flags symbolising their opposition to Lukashenko and chanted for him to leave power and for new elections to be held.
They marched towards a monument that was surrounded by a chain of security service members clad in military uniform, a Reuters witness said.
Until now, the police have handled crowd control on their own, but the defence ministry said it would take on security around national memorials and issued a direct warning to protesters.
The interior ministry issued its own statement warning that any unsanctioned protests would be considered illegal. It said 22 people had been arrested on Saturday when smaller-scale protests took place across 55 towns and cities.