South Korea has initiated live-fire drills for the first time since North Korea shelled a local island, killing at least four. This escalates the tensions and could lead to further attacks. These military exercises are what North Korea claimed led to the artillery shelling of Yeonpyeong; however, they are confined to areas far away from Yeonpyeong, and the more disputed waters along the Korean peninsula.

Meanwhile, the US, Japan and South Korea will hold talks in Washington on the situation, after President Obama and Hu Jintao finally spoke, after nearly two weeks, about the incident.

In a telephone call earlier, Mr Obama urged Chinese President Hu Jintao to work with the US to send “a clear message” to North Korea that its provocations against the South were “unacceptable”.

The BBC’s defence and security correspondent Nick Childs says the mere fact of the phone call between the presidents underlines how seriously both Beijing and Washington take the latest tensions.

He says the read-out from the conversation also illustrates the different perspectives: Beijing calling for restraint on all sides and refusing to blame Pyongyang for the recent flare-up; Washington clearly looking to Beijing to lean on North Korea.

The delay itself shows the differing perspectives from China and the US on this matter. China doesn’t want a war on its northern border, and I think that’s it. The US wants a partner in demobilizing North Korea. And they aren’t afraid to pressure the Chinese to make this happen.

In response to the North Korean moves and apparent Chinese acquiescence, Washington is moving to redefine its relationship with South Korea and Japan, potentially creating an anti-China bloc in Northeast Asia that officials say they don’t want but may need [...]

“The Chinese embrace of North Korea in the last eight months has served to convince North Korea that China has its back and has encouraged it to behave with impunity,” said a senior administration official speaking on the condition of anonymity because of the sensitivity of the subject. “We think the Chinese have been enabling North Korea.”

The Korean Peninsula, the official added, has catapulted to the “top of the security agenda when President Hu comes here . . . and the Chinese are aware of it.”

Apparently, Hillary Clinton wondered out loud in a Wikileaks-released cable, in reference to China, “How do you deal toughly with your banker?” No policymaker has figured that one out yet.

I also think you have to look at the inking of the South Korea trade deal with this context. The US is definitely trying to build an Asian alliance outside of China.