Is this Russian Vine dead?

I had a Russian Vine growing up my shed. I wanted to kill it because we want to build a garden room in place of the shed, and I understand that it is particularly partial to concrete foundations.

I cut down the foliage last year, cutting it down to about 2ft off the ground, and basically did nothing else. This year, I sprayed the new growth with roundup. About 2 weeks ago, I cut the stump down a bit more to about 1ft above ground, cut some notches into the trunk, and spread stump killer on the trunk.

I attach a picture of what the stump looked like today - basically the same as it did when I put the stump killer on it.

I am hesitant to believe that I have killed it: it seemed just a bit too easy, given what I have read about Russian Vine. However, my wife wants to move the garden room project on, so I need to know if it is dead or not.

So:

1. Is this dead?
2. If you can't tell just from this pic, what should I be looking for (/what should I not see)
3. How long should I wait before celebrating victory?

Thanks in advance,

Andy.