Newspaper headlines: 'Trump one step from war'
The Daily Telegraph opens with a striking depiction of the moment 59 US missiles were fired at a Syrian air base while commander-in-chief Donald Trump hosted Chinese president Xi Jinping in Florida.
"As he tucked into a New York strip steak and Thumbelina carrots in an ornate private dining room at Mar-a-Lago, Donald Trump knew the bombs would be in the air by the time he finished his chocolate sorbet," it reports.
The paper says Theresa May and other British officials had been briefed 10 minutes earlier.
The Daily Mirror suggests Mr Trump's decision was influenced by tweets posted by his daughter Ivanka, describing her "heartache" at seeing images of the victims of the gas attack.
The Times provides details of the Tomahawk missile that did the damage, chosen, it says, because it can be launched from 1,000 miles away with such a high degree of accuracy that it can be fired through the window of a building.
The Guardian says the Pentagon believes Russian officers had been inside the air base when a shell filled with sarin was loaded on to a Syrian jet although it says US intelligence has not established whether the Russians knew of the planned attack.
The Daily Express says there are growing fears that Mr Trump's response could be "the opening salvo in a war between the world's two biggest military powers".
The Daily Mirror's political editor Jack Blanchard writes that "any sustained Western attack... would bring the world to its most dangerous point since the end of the Cold War".
Disturbing images of the terror attack in Stockholm are reproduced across the papers.
Bodies lying on the ground, covered with blankets; the stolen lorry, on fire, embedded in a department store window; a grainy CCTV still of the suspect.
"Mown Down" is the headline in The Sun. The Daily Mail describes it as a "copycat truck attack" with echoes of Nice and Berlin.
The Daily Express predicts that "Europe's big cities are braced for an upsurge in terror outrages" with specialist troops put on standby in neighbouring Denmark and Norway.
According to the Financial Times, Brussels is planning to exclude the UK from the regular updates on EU trade policy because of concerns it could take advantage of sensitive information to gain its own post-Brexit deals.
Many EU leaders are said to be worried that Britain could "out-bid the EU in future negotiations" despite the government promising to be "loyal" while it remains a member state.
A report seen by the Times is said to be calling for Southern Rail to hand some of its services to other operators so it can concentrate on its London commuter routes.
The paper says the review will "stop far short of demanding the full break-up or renationalisation" of Southern's parent company Govia Thameslink Railway but will advocate "practical steps" to "reduce the size and scope of the franchise" which has been dogged by a year of delays, cancellations and strikes.
Oscar-winner Glenda Jackson offers a theory in the Daily Mirror about why mumbling is such a problem in modern television dramas.
The veteran actress believes younger thespians are being denied the chance to hone their craft in the theatre.
She says that is down to the demise of the repertory system.