While the situation on Syria remained fluid -- with the US president expected to confer with Britain and France later Thursday on possible retaliation -- investors welcomed a statement on Twitter from the US president that suggested he might hold off on an imminent strike.

US and European markets had fallen on Wednesday on worries about US action on Syria, following a more bellicose tweet.

"A tweet-turnaround from Trump ... was the main driver of growth, lifting the majority of the markets out of the red and into the green," said Spreadex analyst Connor Campbell.

Other factors in the rally included optimism over the upcoming corporate earnings season and signals the US president will consider rejoining a major Pacific trade pact.

US stocks finished solidly higher, with the Dow Jones Industrial Average climbing 1.2 percent

Frankfurt closed with a gain of 1.0 percent, while Paris won 0.6 percent.

Investors welcomed Trump's statement on Syria before US trading opened, after he seemed to suggest the prior day that bombs could drop at any minute.

"Never said when an attack on Syria would take place," Trump tweeted early Thursday. "Could be very soon or not so soon at all!"

"The president's tweet seemed to help ease fears regarding the situation in Syria -- or, at the very least, temporarily put it out of investors' minds," Briefing.com analyst Patrick O'Hare said.

Analysts also were encouraged that Trump was working more closely with US allies on Syria.

Trump met with military advisors on Syria later Thursday and was to speak with French President Emmanuel Macron and British Prime Minister Theresa May on the action the allies might take, White House press secretary Sarah Sanders said.

The White House announcement came after May held an emergency cabinet meeting on the situation in Syria, where dozens of people were killed last weekend in a suspected toxic gas attack on Douma, the largest town in a former rebel stronghold outside Damascus.

Stocks also were also boosted by optimism over the upcoming earnings period, which begins in earnest Friday with reports from JPMorgan Chase and other large banks.

And Trump has directed his trade officials to review reentering the 11-nation Trans-Pacific Partnership, which he exited in one of his first acts as president in January 2017.

- Aiming for Norwegian? -

Away from geopolitical worries, there was eye-catching news in the aviation sector.

International Airlines Group (IAG), the owner of British Airways and Spanish carrier Iberia, is mulling a potential takeover of low-cost airline Norwegian Air Shuttle after building up a minority holding, it said Thursday.

Norwegian's shares shot 47 percent higher on the Oslo stock exchange.

Shares in EasyJet were among the top gainers on the FTSE 100 in London, climbing 3.2 percent, while shares in IAG declined 1.1 percent.

Shares in Ryanair were up more than 2 percent in late trading in Dublin.

- Key figures around 2100 GMT -

New York - Dow: UP 1.2 percent at 24,483.05 (close)

New York - S&P 500: UP 0.8 percent at 2,663.99 (close)

New York - Nasdaq: UP 1.0 percent at 7,140.25 (close)

London - FTSE 100: UP less than 0.1 percent at 7,258.34 (close)

Frankfurt - DAX 30: UP 1.0 percent at 12,415.01 (close)

Paris - CAC 40: UP 0.6 percent at 5,309.22 (close)

EURO STOXX 50: UP 0.7 percent at 3,443.30 (close)

Tokyo - Nikkei 225: DOWN 0.1 percent at 21,660.28 (close)

Hong Kong - Hang Seng: DOWN 0.2 percent at 30,831.28 (close)

Shanghai - Composite: DOWN 0.9 percent at 3,180.16 (close)

Euro/dollar: DOWN at $1.2329 from $1.2367 at 2100 GMT on Wednesday

Dollar/yen: UP at 107.26 yen from 106.79

Pound/dollar: UP at $1.4230 from $1.4177

Oil - Brent North Sea: DOWN 4 cents at $72.02 per barrel

Oil - West Texas Intermediate: UP 25 cents at $67.07 per barrel

burs-jmb/hs

IAG - INTERNATIONAL CONSOLIDATED AIRLINES GROUP

NORWEGIAN AIR SHUTTLE