Washington's swift response overnight Thursday to Syria's alleged chemical weapons attack wasn't merely an impulsive response from a US president known for his impulsive behavior, but also contained a message to his guest at the time - Chinese President Xi Jinping - analysts say.

President Donald Trump informed his guest of the US strike as their dinner was winding down on Thursday evening in Florida. China is North Korea's patron and arguably its only real ally, and the agenda at the summit included the issue of how to thwart Pyongyang's nuclear ambitions.

For years the US has pressed China to rein in the North - specifically, its nuclear weapons and long-range missile programs, which Pyongyang says it is pursuing with the aim of being able to strike the United States.

The strike in Syria lends some more weight to Trump's recent threat of unilateral action against North Korea if Beijing fails to bring pressure to bear on its neighbor to stem its nuclear weapons program.

A message sent

Kim Yong-Hyun, a professor at Dongguk University, said the strike against Syria was a statement of intent that was meant for a broader audience.

"It signals to Pyongyang that the US has a new sheriff in town who isn't hesitant about pulling his gun from the holster," Kim said.

On Saturday, Pyongyang responded, calling the US strike "an unforgivable act of aggression" that showed its decision to develop nuclear weapons was "the right choice a million times over."

Russia also condemned the US airstrike, while Germany supported it.

Implied threat

The Trump administration, of course, hopes the North will internalize a different message: namely, that it should abandon its weapons program to avoid a US attack.

But the message Washington wants to convey may not be the one received in Pyongyang.

"In the long term, US military actions overseas won't help curb the North's nuclear pursuit," Kim said.

'Unlikely to have an effect'

Joel Wit, a senior fellow at the US-Korea Institute at Johns Hopkins University, said, "Trump's attack on Syria is unlikely to have any significant effect on a North Korea that is already well-versed in the threat posed by the United States."

When the US invaded Iraq in 2003, the North Korean leader at the time, Kim Jong-Il, disappeared from public view for around six weeks - and it was widely believed that he had gone into hiding for fear of a US attack.

Chang Yong-Seok, a senior researcher at the Institute for Peace and Unification at Seoul National University, said Kim's son, current leader Kim Jong-Un, had no reason to take such precautions.

"Armed with nuclear weapons, he would hardly flinch at the attack in Syria," Chang said.

As if to underline the point, North Korean state media released photos of a smiling Kim inspecting a mushroom farm.

bik/tj (AFP, Reuters)