WASHINGTON: Working to display a united front on Thursday, the US and key Asian countries sought to put more pressure on North Korea as world leaders opened a nuclear security summit in Washington.

The summit offers US President Barack Obama his last major chance to focus global attention on disparate nuclear security threats before his term ends early next year.

Though nuclear terrorism and the Daesh killings top this year’s agenda, concerns about North Korea’s nuclear weapons program are also commanding focus.

Those long-simmering concerns have escalated of late following the North’s recent nuclear test and rocket launch.

China’s influence over the North was the front and center later on Thursday.

Though frictions with China remain high, the US was encouraged by China’s role in passing stringent new UN sanctions on North Korea, its traditional ally.

Now the US is pressing Beijing to implement those sanctions dutifully.

“The international community must remain united in the face of North Korea’s continued provocations, including its recent nuclear test and missile launches,” Obama wrote in an op-ed appearing Thursday in The Washington Post. He added that the recent UN sanctions “show that violations have consequences.”

The US and South Korea have been discussing whether to deploy a US missile defense system called THAAD, or the Terminal High-Altitude Area Defense, in South Korea to counter the threat from the North.

China has resisted that step out of concern it would also give the US radar coverage over Chinese territory, and Russia opposes it as well.