The United States has been cornered and left with few options in the current stand-off with North Korea, analysts say. With rapid advances in its nuclear and missile programme, the calculus has shifted in Pyongyang's favour.

The US wants North Korea to give up its nuclear weapons as a precondition for talks, but Pyongyang has refused. With no diplomatic avenues in sight, analysts expect the North to conduct more missile tests, possibly as early as this month, to signal disapproval of annual joint drills by US and South Korean forces.

But more voices in the US are calling for dialogue with North Korea without preconditions. "We need to have dialogue with them... accept the fact they are a nuclear power," former Central Intelligence Agency director James Clapper said on Tuesday.

North Korea expert Sue Mi Terry of Bower Group Asia told The Straits Times: "If (the US) wants talks, we have to drop the insistence that they (North Korea) denuclearise. But the US is not going to do it, that's why we have this impasse.

"North Korea will continue on its path. It will conduct more ICBM (intercontinental ballistic missile) tests and probably even a nuclear test, until they feel they have completed their programme and are capable of attacking mainland US with a nuclear weapon. Unfortunately, we are stuck and this just has to play out."

The US is banking on much wider and tighter sanctions to raise the cost to North Korean leader Kim Jong Un. "Up until now, serious full-on sanctions have never been tried," Mr Danny Russel, a senior fellow at the Asia Society Policy Institute, told The Straits Times. "Creating maximum obstacles and headwinds" to impede the North's ability to advance its nuclear missile programme was an important part of forcing Mr Kim into "tactical accommodations".

Analysts are sceptical. "That all states will faithfully implement (the sanctions) is unrealistic," said Dr Sung Yoon Lee, professor of Korean studies at the Fletcher School of Law and Diplomacy at Tufts University. "North Korea has no reason to be deterred."

Dr Bong Young Shik of Yonsei University's Institute for North Korean Studies told The Straits Times: "North Korea... is still trapped in the stage of escalation of tension and exchange of belligerent words."

Mr Russel said: "At one level, this is not a nuclear war scenario, this is really a psychological war. The US has a very compelling deterrent capability which Kim Jong Un is entirely aware of, and so he is navigating in a very small space. The question is, can the world convince Kim Jong Un... that he needs to reverse course and negotiate a rollback of pressure in exchange for a rollback of his programme?"

South Korean analysts believe the US and North Korea will eventually resume talks. Yonsei University's international relations professor Kim Hyung Jong said: "What North Korea eventually wants is to secure its regime... which needs the US guarantee."

"The US also does not have many options," he said. "In the end, the US may have to have a dialogue with North Korea."

In Beijing, Professor Shi Yinhong, a US expert at Renmin University, told The Straits Times that China hoped the US would turn towards dialogue, but its influence was limited as the US, North Korea and South Korea were unwilling to talk. "China will continue to persist in appealing to both sides to return to the six-party talks" he said.

In Washington, Dr Balbina Hwang, a visiting professor at Georgetown University, told The Straits Times: "It is North Korea that has to agree to talks. It's not only up to the US. Sanctions don't mean the US is refusing to talk."

But she cautioned against overstating the crisis. US President Donald Trump's belligerence was typical of his style, she said. And Mr Kim Jong Un had threatened Guam, not US assets in South Korea, Dr Hwang noted. "We need to calm down," she said. "There is no tension on the Korean peninsula."

ADDITIONAL REPORTING BY CHANG MAY CHOON AND GOH SUI NOI