A look at the North Korea crisis

As the world waits and watches for an expected North Korean ballistic missile test, the U.S. and its allies are prepared to respond. U.S. officials are conceding that North Korea may be increasing its nuclear capabilities, but they don't expect a nuclear strike. They suggest that other military moves by Pyongyang involving artillery attacks or shelling of nearby South Korean islands could actually present a more serious threat in triggering a conflict.

WHY ALL THE HUBBUB

Since the 1950-53 Korean War, North Korea has feared that Washington is intent on destroying the regime. The U.S. worries that Pyongyang will re-ignite the conflict with South Korea, and is uneasy because little is known about Kim Jong Un, the North's new, young leader, and considers him unpredictable. Both sides have ratcheted up the rhetoric and military muscle moves in recent weeks. North Korea threatened a pre-emptive strike against the U.S., and conducted an underground nuclear test in February and a rocket launch in December. The threats are seen as an effort to pressure Washington and Seoul to change their North Korean policies and convince the North's people that their new leader is strong enough to stand up to its foes. U.S. and South Korean troops have been conducting annual joint military drills in the region since early March, including bringing out nuclear-capable stealth bombers and fighter jets in what the U.S. Air Force acknowledged was a deliberate show of force.

NORTH KOREAN MISSILES

North Korea has been steadily working to display an increasing capability to launch missiles. Last year it failed in an attempt to send a satellite into space aboard a long-range rocket. A subsequent launch in December was successful, and that was followed by the country's third underground nuclear test on Feb. 12. U.S. officials believe the North is preparing to test fire a medium-range "Musudan" missile. And a section in a new Defense Intelligence Agency assessment concludes with "moderate confidence" that the North could deliver nuclear weapon by ballistic missiles. The report notes that the delivery system is still not considered reliable.

U.S. RESPONSE

The North American Aerospace Defense Command, or NORAD, which has responsibility for U.S. homeland defense, is watching the region via satellite and the USS Fitzgerald and the USS John S. McCain, Navy destroyers armed with sophisticated missile defense systems, have been positioned to best be able to detect and track a missile launch. The U.S. is confident it would be able to shoot a missile down, but would do so only if it appears to be a threat to America or its allies. The U.S. is also prepared to provide military assistance to South Korea in the event of any other type of attack by the North.

WHAT THEY'RE SAYING

Secretary of State John Kerry warned North Korea not to conduct a missile test, saying it will be an act of provocation that "will raise people's temperatures" and further isolate the country and its people. President Barack Obama said his administration would "take all necessary steps" to protect American citizens and he urged Pyongyang to end its threats. North Korea has issued no specific warnings to ships and aircraft that a missile test is imminent. And the country has begun festivities celebrating the April 15 birthday of the country's late founder, Kim Il Sung, which is considered the most important national holiday. China has been a longtime political, military and economic backer of North Korea and is considered to have more real leverage over the North. U.S. officials say there are indications Chinese leaders have become frustrated with Pyongyang's recent behavior and rhetoric. In a positive development for the U.S., China agreed publicly to work with the U.S. to achieve the goal of a nuclear-free Korean peninsula.