There, NATO leaders will formally endorse the revamp which puts more troops into eastern European member states as part of a "deter and dialogue" strategy, meant to reassure allies they will not be left in the lurch in any repeat of the Ukraine crisis.
"We will discuss how NATO can do more to project stability... and at the same time address how NATO can continue to adapt to a more assertive Russia to find the right balance between defence and dialogue," Stoltenberg told reporters.
While the focus has been on the eastern flank, there are also growing challenges to the south, with conflict in Syria and Iraq, and instability across North Africa.
But rather than NATO taking a leading role there, Stoltenberg said it was better for the alliance to help struggling countries help themselves to cope with terrorist threats such as Islamic State (IS).
The EU meanwhile is grappling with the worst migrant crisis since the end of World War II and the bloc wants increased cooperation with NATO to tackle the problem, notably in bolstering the UN-backed government in Libya where IS has recently gained ground.
- Mutual suspicions -
"I think you have to remember where this started," said a senior US official.
"NATO took these measures because Russia chose to invade and occupy Crimea and then move into eastern Ukraine. The concern ... was to ensure that this was not the beginning of a broader move that might threaten NATO territory."
In another move likely to infuriate Moscow, NATO signed an accession accord with the tiny Balkan state of Montenegro on Thursday.
Prime Minister Milo Djukanovic said NATO membership was a major step forward for his country "and will help bring about stability in the region and beyond."
Georgia, which fought a brief 2008 war with Russia , is also seeking membership but when asked Thursday if Tbilisi could expect similar progress, Stoltenberg notably stopped short of commenting directly on its accession prospects.
Instead, he stressed NATO would continue to boost cooperation, including military training, with the former Soviet republic.
- Avoid new arms race -
Stoltenberg had cautioned Wednesday against a new arms race, stressing the alliance upgrade was purely "defensive, proportionate and in line with our international obligations."
Stoltenberg convened the first NRC since June 2014 last month, which he said produced a "frank" but also "useful" exchange.
"I think there will be a meeting... a number of allies want it quite badly and the rest of us think it is not worth fighting about," one source said, downplaying the NRC 's importance.