The Scottish Secretary has hailed the Prime Minister's plan for Britain to leave the European Union on October 31 as a chance to introduce new farming funding.
Writing for The Times Scotland, he promised to "help the Prime Minister deliver Brexit" and "sweep away the cloud of uncertainty that has been hanging over us".
As well as farming, the Dumfries and Galloway MP used his piece to focus on fishing and the European Court of Justice (ECJ).
In the column Mr Jack wrote: "When the UK leaves the EU, Scotland will finally take back control of Scottish fishing waters, among the richest in the northern hemisphere.
"And once we are out of the EU, we will have a historic opportunity to introduce new farming funding schemes to support Scottish farmers - and we will make sure that they get a better deal.
"Post Brexit, Scottish people will not want to go back to living under the ECJ, they will not want to hand back control of fishing.
"By strengthening the union, by showing the many advantages of belonging to the UK, we will also lift the second cloud of uncertainty facing Scotland, the First Minister's threat of a second independence referendum.
"That is a brighter vision than narrow, angry nationalism can offer. And it is why I am certain we can, and will, make a winning case for the union in the months and years ahead."
On Wednesday, official figures revealed Scotland's fiscal deficit fell for the third year running - but is still spending £12.6 billion more than it receives.
Government Expenditure and Revenue Scotland (Gers) statistics revealed Scotland's deficit is 7% of the country's gross domestic product (GDP), compared with the UK's 1.1% fiscal deficit.
Mr Jack said the figures "show clearly how Scotland benefits from being part of a strong United Kingdom".
He reiterated his position in the newspaper column, also hitting out at Scottish nationalism despite accepting "challenging times for our union".
He wrote: "Yesterday [21 August] the Scottish Government published the annual 'Government Expenditure and Revenue Statistics', which show a nearly £13 billion black hole in the Scottish Government's finances.
"But being part of a strong UK means support for Scotland's economy. Despite contributing less in taxes, Scotland receives a bigger share of public spending. Scottish nationalism, however, chooses not to recognise that.
"It's all about finding something at which to take offence. So, they pick fights about flags on packaging, they scour news bulletins and political shows for examples of imaginary bias.
"The Scottish Government spent much of last year railing against an imaginary 'power grab' - even though they were unable to name a single power that Holyrood would lose when we leave the EU.
"In fact, scores of new powers will lie with the Scottish Parliament after October 31.
"They claim that 'devolution is broken'. But that is just another fiction. Again, the reality is very different. It is the Nationalists who seek to break devolution so they can replace it with independence."