07/01/2016 05:57 GMT | Updated 07/01/2017 05:12 GMT

Trident Is the Wrecking Ball Which Will Destroy Jeremy Corbyn's Game of Political Jenga

Jeff J Mitchell via Getty Images

Tentatively, slowly and cautiously - how Jeremy Corbyn carries out his reshuffle is how the rest of us play Jenga.

The Labour leader spent three days gently poking at the blocks in the tower that is his Shadow Cabinet, trying to work out which ones could be removed without the whole structure falling down around him.

Michael Dugher, Pat McFadden and Maria Eagle were all eased out. Sure, the tower wobbled slightly, but it remains standing.

However, in the next few months an issue will come to fore that will see the whole edifice come down upon his head: Trident.

If Labour Party changes its policy and backs unilateral disarmament, there will be mass resignations from the Shadow Cabinet.

One Shadow Cabinet minister told me they would would definitely walk if the policy was changed. "Look at the people who have spoken out against it: Tom Watson, Vernon Coaker, Maria Eagle, they would all go too."

A junior Shadow government member told me before Christmas that Trident would be the big issue for Labour of the first few months of 2016. They too said they would quit if the party's policy changed.

At Labour's conference in Brighton last year, the divisions at the top of the party over whether to renew Trident were exposed to the South coast sunshine.

Corbyn, in one of his thinking-out-loud moments, revealed if he was Prime Minister he wouldn't sanction the use of nuclear weapons in any circumstances.

Then-Shadow Defence Secretary Maria Eagle called the remarks "unhelpful", particularly as the party was about to embark on a review of its defence policy.

The same review which former London Mayor Ken Livingstone, himself a unilateralist, was appointed to oversee in November - a decision which was questioned by now ex-Shadow Defence Minister Kevan Jones.

For the Tories, this is a political gift.

Even if Labour's defence review backs renewing Trident, Corbyn is a known and confirmed unilateralist. David Cameron would have endless fun taunting the opposition for having a leader who would actually rebel against his own party's policy.

Of course the Tories need not wait for Labour to complete its review. Cameron could force a vote on whether to renew the nuclear submarines which carry the weapons before Labour has its ducks in a row.

As it is, the official policy of Labour is to support the renewal. So again, Corbyn could be forced to rebel against his own party. Not that he is unused to that, but rebelling as leader? That would be something special.

If he tries to force his Shadow Cabinet to vote against renewal, or even backs a free vote, people will walk. The blocks will fall.

Corbyn will be left with a very small Jenga tower indeed.