One day after announcing America's unilateral pullout from a treaty to prevent nuclear proliferation with Russia, Donald Trump warned that the US will bolster its nuclear arsenal to put pressure on Russia and China. Speaking to reporters on Sunday, he repeated his belief that Russia has violated the 1987 Intermediate-Range Nuclear Forces (INF) treaty. Russia denies this.

The Cold War-era treaty banned medium-range missiles, reducing the perceived Soviet threat to European nations. Russia has warned it will respond in kind if the US develops more weapons. Mr Trump said the US would build up its arsenal "until people come to their senses".

British Prime Minister Theresa May urged restive lawmakers to back her in the final stages of Britain's exit from the European Union, saying talks were in their most difficult phase even if a deal was close. After facing some of the fiercest attacks to date over her Brexit plans since again failing to clinch a deal at an EU summit last week, May tried to calm passions in parliament where her strategy has angered eurosceptics and EU supporters alike.

"Serving our national interest will demand that we hold our nerve through these last stages of the negotiations, the hardest part of all," May told parliament. Financial markets seized on the possibility that May could be toppled as prime minister by rebels in her Conservative Party, driving sterling below $1.30 to its lowest since Oct. 4.

Chinese leader Xi Jinping opened one of the world's longest bridges on Tuesday, during a tour to southern China that is seen by some as an opportunity for Beijing to reaffirm its commitment to economic liberalisation.

The Hong Kong-Zhuhai-Macau bridge is made up of nearly 35-km (22-mile) bridge and road sections and a 6.7 km (4-mile) tunnel, and has been dubbed the longest "bridge-cum-tunnel sea crossing" in the world. It will link the financial hub of Hong Kong to the relatively less developed western reaches of the Pearl River Delta in Guangdong province, as well as the former Portuguese colony and gambling hub of Macau. Xi said nothing during the inauguration of the bridge on Tuesday morning other than to declare it officially open to a burst of fireworks projected onto a screen behind him.

Oil prices dipped on Tuesday after Saudi Arabia pledged to play a "responsible role" in energy markets, although sentiment remained nervous in the run-up to U.S. sanctions against Iran's crude exports that start next month. Front-month Brent crude oil futures (LCOc1) were at $79.62 a barrel at 0427 GMT, down 21 cents, or 0.3 percent, from their last close.U.S. West Texas Intermediate (WTI) crude futures (CLc1) were at $69.26 a barrel, dropping 10 cents from their last settlement. Top crude oil exporter Saudi Arabia has pledged to keep markets supplied despite its increasing isolation over the killing of Saudi journalist Jamal Khashoggi.

There has been concern that just as markets tighten with the start of the U.S. sanctions against Iran, Saudi Arabia could cut crude supply in retaliation for potential sanctions against it over the Khashoggi killing. Trying to dismiss such worries, Saudi Energy Minister Khalid al-Falih said on Monday that "there is no intention" for such action, and that Saudi Arabia would play a "constructive and responsible role" in world energy markets.