Footage of Iran’s Revolutionary Guards seizing control of the British-flagged oil tanker, Stena Impero, appears on a number of Sunday’s front pages.
The Sunday Telegraph says ministers are drawing up plans to target the Iranian regime with sanctions in response.
According to the paper, Foreign Secretary Jeremy Hunt is expected to announce a package of diplomatic and economic measures in the Commons, including possible asset freezes.
In the Sunday Times, an un-named former cabinet minister accuses Mr Hunt and outgoing Prime Minister Theresa May of being distracted by the Tory leadership contest and having “taken their eyes off the ball” over the Iranian threat.
A similar accusation is made by the former First Sea Lord, Admiral Lord West, in the Observer.
He says whoever wins the contest is going to have to face a major international crisis as soon as he’s in post. “It can’t be ignored because of Brexit,” he warns.
For its lead story, the Sunday Times says senior figures from five EU countries have established contacts with Boris Johnson’s team in a bid to thrash out a new Brexit plan that would avoid a no-deal departure.
It reports that Simon Coveney, the deputy Prime Minister of Ireland – one of the countries – has written an article for the paper saying the withdrawal agreement is “not up for negotiation”, but also making clear that Dublin wants to avoid a no-deal Brexit at all costs.
The Chancellor, Philip Hammond, is pictured on a number of front pages loading suitcases into his official car in Downing Street, which the Sunday Telegraph says sent Whitehall tongues wagging.
But the Mail On Sunday leads with Mr Johnson’s plans for moving into Number Ten.
According to the paper, Mr Johnson – the favourite to become prime minister – has been criticised for spending thousands of pounds of taxpayers’ money on new furniture, including a bed, because his estranged wife has kept his belongings.
The paper says he had told civil servants he “didn’t have any stuff”.
The Mail reveals that the NHS in England has failed to recover nearly three-quarters of the largest bills owed by ineligible foreign patients.
Its investigation found examples such as a single patient running up a bill of nearly £420,000 at a hospital in Birmingham; and scores of patients failing to pay a penny towards care costing £100,000 or more – including 14 at one hospital alone.
It says the scandal is estimated to cost the NHS up to £280m a year.
According to the Observer, this is the year of the last-minute summer – with huge numbers of people having delayed booking their holidays until the last few weeks, thanks to what it calls a messy cocktail of weather, politics and a plunging pound.
Spain – particularly Tenerife and Mallorca – remain the most popular destinations, it reports.
But the biggest gainers this year include Tunisia, Sardinia and Bulgaria, at the expense of Orlando, Dubrovnik and Dubai.