This move will increase Russia's strategic isolation after its February invasion of Ukraine and subsequent military conflicts there.
The NATO summit's 30 ambassadors and permanent representative will officially approve the decisions made last week, when Russia's neighbour Finland and Sweden were invited to join the military club.
Despite the accord in the alliance, the approval of the parliamentary body in Turkey could still be a problem for their final inclusion as member states.
Recep Tayyip Turkey's leader warned last week that Ankara could block the process if they fail to meet Turkey's demands to extradite terror suspects linked to Kurdish groups outlawed or the network of an exiled clergy accused of a failed coup in Turkey in 2016.
He stated that Turkey's Parliament might refuse to ratify this deal. This is a serious threat, as NATO accession must be officially approved by all the 30 member countries. Each state has a blocking right.
Both nations will be joining NATO more deeply with Tuesday's expected signature-off. They were close partners and have attended meetings that dealt with issues that directly affected them. They can attend any meeting of the ambassadors as official invitees even though they don't yet have voting rights.