US president Donald Trump thanked China for its efforts to rein in North Korea's nuclear ambitions, but signalled a possible new approach by the US to dealing with Pyongyang, amid anger over the death of student Otto Warmbier who was held there for seven months.
"While I greatly appreciate the efforts of President Xi and China to help with North Korea, it has not worked out. At least I know China tried!" Mr Trump wrote on Twitter.
The death of Mr Warmbier, who came home in a coma after being imprisoned for stealing a propaganda poster, has ratcheted up tensions in the region. Satellite pictures showing that the North might be preparing a sixth nuclear test have added to the regional unease.
North Korea’s last nuclear weapons test was in September but since then it has conducted numerous missile launches, in defiance of United Nations’ bans, and it has pledged to develop an intercontinental ballistic missile capable of reaching American shores.
Help expected
Mr Trump had earlier indicated that he expected significant help from China after a meeting with President Xi Jinping in Florida in April and his comments form the backdrop to the Diplomatic and Security Dialogue in Washington.
The meeting brings secretary of state Rex Tillerson and defence secretary James Mattis face to face with China's top diplomat Yang Jiechi and Gen Fang Fenghui, chief of joint staff of the People's Liberation Army.
While counter-terrorism and China's controversial territorial moves in the South China Sea will feature at the talks, the main aim will be to find ways to tighten the screws on North Korea. Washington and the West want more sanctions, such as an oil embargo, but China and Russia are resisting any further sanctions.
The nationalist newspaper Global Times warned that Washington might put even more pressure on China after Mr Warmbier's death.
“China has made the utmost efforts to help break the stalemate in the North Korean nuclear issue. But by no means will China, nor will Chinese society permit it to, act as a ‘US ally’ in pressuring North Korea,” it said.
"If Washington decides to impose third-party sanctions on several Chinese enterprises, it will lead to grave friction between China and the US over the Korean Peninsula issue," said the Global Times, whose views often reflect those of Communist Party officials.
Strong links
Although Mr Trump’s remarks could be read as confrontational, there are other signs that relations remain strong.
Mr Trump's daughter, Ivanka Trump, and her husband, White House senior adviser Jared Kushner, have been invited by the Chinese government to visit the country later this year.
Ms Trump’s company was recently awarded a range of new trademarks in China. Labour activists investigating a shoe company that makes products for her firm have been detained by authorities.
Mr Kushner’s family business has been criticised over its use of a visa programme to lure wealthy Chinese with green cards in exchange for investing in US projects.
Meanwhile, the South Korean government says it will step up efforts to free its six people held in the North, including three pastors. Pyongyang is also holding one Canadian and three Americans in captivity.
