North Korea - a vexing problem for the US
Every spring, cherry trees blossom in Washington, and North Korea's bluster and rhetoric reaches a fiery pitch.
Just as predictable as the changing seasons is Pyongyang's reaction to the annual military exercise between South Korea and the US, known as Foal Eagle.
The US says it has detected no signs that North Korea is actively preparing to go on the offensive - there has been no large-scale mobilisation of forces, for example.
Pyongyang's threats are usually conditional - if there is a real danger of a US attack, there will be a response, or a pre-emptive strike.
The tension usually goes down when the exercises end - until the next round of theatre and threats. But the possibility of an accident provoking a military confrontation is always real.No creative ideas
North Korea has been a vexing problem for Washington for years, and so far the Obama administration has also failed to successfully engage Pyongyang and break this cycle - or curb its nuclear programme.
This year, the threats emanating form North Korea have sounded even more bombastic for several reasons.
There's a new young leader sitting in Pyongyang who's still asserting himself domestically and consolidating his power.
And South Korea has just elected its new president, Park Geun-hye - the country's first female leader. So, Kim Jong-un is - no doubt - testing her too.
The US reaction has remained mostly the same - with a few variations, officials in Washington repeat the line that North Korea's actions are not helpful and only further isolate the reclusive nation. There seem to be no creative ideas on the horizon.Different rationale
During the Clinton administration, the US repeatedly cancelled military exercises to assuage Pyongyang's fears and defuse tension.
End Quote Joseph DeTrani America's Intelligence and National Security Alliance
The North Koreans know the US and China are available in the six-party talks - their rhetoric is over the top and puts them in a difficult position”
But more recently, Washington has matched the intensity of Pyongyang's rhetoric with a display of hardware.
After a deluge of 20 threats in a just a few weeks, the Obama administration also dispatched B-2 stealth bombers over the Korean peninsula.
The move was also meant to decrease pressure on South Korea to take unilateral action to sound tough in the face of its northern brethren.
But every attempt by the US and the international community to hold Pyongyang accountable, with sanctions for example, leads to even more erratic behaviour by the North Koreans.
And every time the US ignores Pyongyang's pleas for attention, responding with a resolve to continue military exercises, the North Koreans are further infuriated - partly because their thinking is driven by a different rationale.
They perceive US-South Korean defensive military exercises as potentially offensive, and analysts say the North Koreans believe their nuclear weapons are the only thing keeping them safe from a US attack.Secret missions
President Obama spoke at the start of his first term about his willingness to extend a hand if America's foes were willing to unclench their fist.
Efforts to restart the six-party talks, which stalled in 2009, have failed.
And Pyongyang's behaviour makes it difficult for Mr Obama to be bold and engage in open, direct talks with the North Koreans without risking being lambasted by critics for caving in to threats and legitimizing Kim Jung-un.
Administration officials did travel to North Korea on secret missions last year in an effort to persuade the newly-anointed leader to moderate his foreign policy.
One of the trips took place in April 2012 and was led by Joseph DeTrani - a North Korea expert who then headed America's National Counter-Proliferation Center.
Mr DeTrani, who is now president of the Intelligence and National Security Alliance, an industry group, would not openly confirm to the BBC that he had been on a mission to Pyongyang.
But he spoke about the need for diplomacy while indicating that the American approach had been rebuffed.
"The North Koreans know the US and China are available in the six-party talks. Their rhetoric is over the top and puts them in a difficult position."
Mr DeTrani added that the US was handling the situation well and that it was up to North Korea to break the cycle.Willing to engage?
US policy towards North Korea is partly driven by Washington's support for Japan and South Korea and efforts to show that the US remains in lock-step with allies in the face of North Korea.
Diplomacy with North Korea takes place mostly through the six-party talks, which also involve Japan, China, South Korea and Russia.
Denuclearisation is always the stated end goal of every discussion. Because of North Korea's fears, justified or not, this often undermines the basis of the talks.
Over the past four years, the Obama administration's posture on North Korea was also dictated by former South Korean president Lee Myung-bak's hardline stance towards the North.
But Christopher Nelson, an Asia expert and vice-president of Samuels International Associates, points out that while the new South Korean leader has responded with tough words to Pyongyang's rhetoric, she has also indicated that if the North Koreans are willing to resume North-South talks, denuclearisation would not have to be the state end goal.
Mr Nelson said there are indications from the North Korean team at the UN that Pyongyang is now willing to engage.
While this still needs to be tested, what's unclear is whether the US is ready to go along with this approach.
In public, and for now, it's unlikely that the US will signal any easing of its policy towards North Korea.
But if Mrs Park persists with her offer, the US could say it respects its ally's choice and will support the approach.
There will be many opportunities to explore this and other diplomatic options in policy towards North Korea.
The South Korean foreign minister is in Washington this week.
The US Secretary of State, John Kerry, will be heading to Asia next week for his first trip to the region in the new job - with stops in Beijing, Tokyo and Seoul.
And President Park herself will meet President Obama in Washington in May.