The US secretary of state, Hillary Clinton, announced a new set of sanctions on North Korea following a visit to the demilitarised zone that separates North and South Korea.

Enmity between the two has persisted since the 1953 armistice, and relations are now under renewed pressure after the sinking of a South Korean warship in March, which caused the death of 46 sailors and which has since been judged the result of a North Korean torpedo attack.

Sanctions will target individuals in Kim Jong Il's regime together with banks that assist the trade of arms and luxury goods that are banned under earlier UN measures. Few specific details about US sanctions were divulged by Clinton though she added that they were not directed at the North Korean people but at the “misguided and malign priorities of their government.”

China, North Korea's principal supporter, accused the US of “aggravating regional tensions” and expressed concern over joint US-South Korean naval exercises due to begin on Sunday.

The openSecurity verdict: Whether the latest round of sanctions will have any long-term effect on North Korea is doubtful; it is already “one of the most sanctioned countries on the planet” according to BBC's John Sudworth. In spite of this, Sudworth contends that sanctions will cause upset, especially as “North Korea had said right from the start that it would see any new sanctions as an act of war.” Taken together with previous UN resolutions against North Korea, new US sanctions will squeeze Kim Jong Il and his ruling circle, making it difficult for them to raise money overseas and freezing the assets of individuals and companies suspected of having ties to weapons proliferation.

Clinton's trip has largely been symbolic and designed to send a message of deterrence to North Korea. Speaking in Seoul on Wednesday, US Defence Secretary Robert Gates associated potential provocations by North Korea to an internal re-structuring within the ruling regime to replace Kim Jong Il, who is believed to be ailing in health. To this end, joint US-South Koran military drills are a clear show of force and designed to ensure that both South Korea and the US return to the negotiating table in the near future from a position of strength.

What is clear from the latest round of US sanctions is that they have stoked tensions between China and the US, at least in the short term. For China, US presence in the region is potentially de-stabilsing. Any potential clash between North and either South Korea or the US could lead to the collapse of North Korea or a flood of refugees in to China. But more significantly, China views joint US-South Korean exercises as a threat to its own security and fears being encircled. It is a feeling heightened by recent US arms sales to Taiwan, with a major January deal leading to the cutting of military ties with the US. Rumours of a further sale of F-16s to Taiwan emerging from the recent Farnborough air trade show, attended by a Taiwanese delegation, could if proven provoke a deeper crisis in US-Chinese relations.

Meanwhile, the US sees China as aggressively posturing. Only today, US Admiral Mike Mullen expressed concern over Chinese buildup saying China has made “fairly significant investment” in amassing equipment including satellites, aircraft and anti-ship missiles. For its part, China says its defence spending is transparent and significantly less than the US, but this will be cold comfort if a Taiwanese report that China is increasing the number of missiles trained on Taiwan, from 1,400 to 2,000, a number which would enable a Chinese strike to destroy a reported 90 percent of Taiwanese infrastructure, is confirmed.

Sudan's Bashir defies arrest warrant

Sudanese President Omar Hassan al-Bashir arrived in Chad on Wednesday in his first visit to a member of the International Criminal Court (ICC) since the court's warrant for his arrest on allegations of war crimes and genocide. Chad reassured the Sudanese government that it would not act on the warrant, with the interior minister telling reporters: "Chad is a sovereign and independent state.... We are not dependent on the injunctions of international organisations."

The two former foes agreed to normalise relations in February after five years of proxy warfare. In his latest visit to the country, al-Bashir will be looking to start a new chapter in relations between the two countries, with the hope that black anti-government militias in Darfur can be deprived of cross-border support.

Rights groups have attacked Chad for denigrating its responsibilities to the ICC and earlier this week accused Sudan of using violence and intimidation to silence opposition to the government. Amnesty International's report, titled "Agents of Fear: The National Security Service in Sudan", says the authorities have used torture, arbitrary detention, and mental and physical intimidation to silence political opponents and human rights defenders.

British PM concludes his first visit to Washington

US President Barack Obama met with British Prime Minister David Cameron on Tuesday to discuss a range of issues including the war in Afghanistan, the global economy, BP's responsibility in an oil spill in the Gulf of Mexico and the controversial release of the Lockerbie bomber, Abdel Basset al-Megrahi. Both leaders said the Scottish authorities' decision to release al-Megrahi was wrong, though Cameron claimed that BP exerted no pressure on Scotland in his release.

Separately, David Cameron raised the extradition of the computer hacker Gary McKinnon during talks with Obama. The prime minister later told BBC Radio 5 Live that he had discussed the prospect that 'some' of McKinnon's sentence, if there is one, is served in a British prison.

President Obama used the opportunity of a joint press conference to stress that the US' relationship with Britain is 'truly special' and that the world is 'more secure and more prosperous' when the two allies work cooperatively.

Suspected rebels attack Russian power plant

Suspected militants attacked a hydroelectric power plant on the Baksan river in Russia's restive North Caucasus region on Wednesday, killing two guards and shutting down the entire facility. Local police say the attackers detonated four explosive devices in the 25-megawatt plant which is situated in the Kabardino-Balkaria republic, a region that has seen considerably less violence in recent years than other semi-autonomous republics such as Chechnya, Dagestan and Ingushetia.