Singapore Airlines will buy 39 planes from American aircraft maker Boeing, in a US$13.8 billion (S$19 billion) deal signed during Prime Minister Lee Hsien Loong's visit to the United States.
US President Donald Trump, who witnessed the signing on Monday at the White House with PM Lee, hailed the deal for creating 70,000 jobs in the United States.
The two leaders said it highlighted the strong commercial relationship between their countries.
PM Lee and Mr Trump also had a four-eye meeting and a working lunch, after which the President said the friendship between Singapore and the US "has never been stronger than it is right now".
PM Lee also announced that Singapore will extend into 2018 its deployment of Singapore Armed Forces assets and personnel to the global coalition against the Islamic State in Iraq and Syria terror group.
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