Bro,
Russia is not providing arms to Taliban to topple US-led Afghan government. When Afghan Taliban splintered after death of Mullah Omar, its
other half pledged allegiance to Abu Bakr al-Baghdadi of ISIS and formulated ISIS-K in Afghanistan. ISIS-K grew in strength with remnants of TTP joining it. Russia is deeply concerned about this development and is pushing all stakeholders in Afghanistan to mend their fences and concentrate on this threat.
https://www.wsj.com/articles/taliban-to-attend-afghanistan-talks-in-moscow-1534776652
https://thediplomat.com/2018/07/why-has-russia-invited-the-taliban-to-moscow/
Russia is not looking forward to fuel current chapter of civil war in Afghanistan. You need to understand that Afghan government won't fall in a day or two, and Taliban's march towards Kabul would be incredibly bloody and thousands more will die in the process. Russia cannot take responsibility for this mess.
Russia will attempt to bring Taliban and Afghan government to the negotiation table in this summit, and this is welcome development. I hope Taliban listen this time.
http://tass.com/politics/1017847
@Crystal-Clear