The tweet has since been deleted.
In advance of today's March, here are photos from a much smaller one held on March 2, just as Russian troops were beginning their incursion into Crimea. The tweet, from activist Victor Korb, says, "We took part in a peaceful picket, 'No to War!' at a time when it was neither vogue nor possible."
Antiwar demonstrations to be held today in Russia:
Antiwar demonstrations against Russia's role in violence in eastern Ukraine are expected to take place on September 21 in Russia's two largest cities, Moscow and St. Petersburg.
Aleksandr Ryklin of the opposition Solidarnost movement said the slogan for the "peace" marches is "Putin, enough lying and making war!"
It was unclear how many people would participate in the marches.
Similar events are planned in other Russian cities and cities outside Russia such as Prague, Berlin, and San Francisco.
The marches coincide with "International Day of Peace" declared by the United Nations that falls on September 21 every year.
This ends our live-blogging for September 20. Be sure to check back tomorrow for our continuing coverage.
Latest on Ukraine:
NATO's top military commander says Russian forces are still operating in Ukraine and that a cease-fire is not working, but he expressed hope a new peace plan could bring progress.
U.S. General Philip Breedlove told reporters in Lithuania on September 20, "as to Russian forces on the ground, yes, they are still inside Ukraine," but did not provide precise numbers.
Breedlove said the September 5 agreement is a "cease-fire in name only." He said violence levels, including the number of artillery rounds fired in the past few days, are as high as prior to the cease-fire.
However, Breedlove said he hopes the agreement announced September 20 for the creation of a buffer zone between Ukrainian government troops and the pro-Russian militants will succeed in stabilizing the situation.
Breedlove was in Vilnius for a meeting of NATO military chiefs. (AFP and AP)