North Korea has fired two ballistic missiles more than 300 miles into the sea in what has been called an 'armed protest ' against military drills in the South . A spokesman for the secretive state threatened 'merciless strikes ' against South Korea and its ally the U.S. , which helps conduct the military drills every year and insists they are just defensive . The war between the two Koreas is still active because it ended in 1953 with an armistice , not a peace treaty , and left a heavily armed two-and-a-half mile wide zone along the border . Making a statement : South Korean TV shows the two missile tests by the North today . The secretive state warned there would be 'merciless strikes ' against routine military exercises carried out south of the border . Training : South Korean soldiers begin the annual military exercises near the demilitarized zone between the two Koreas - which despite its name is one of the most heavily fortified borders in the world . North Korea regularly conducts test firings of missiles , rockets and artillery , but they are often timed to express the country 's dissatisfaction with actions by Washington and Seoul . The missiles were fired early this morning at the start of military drills which are due to run until the end of April . Fired from the west coast , they flew around 300 miles across the width of North Korea before landing in waters off the east coast , according to South Korea 's Defense Ministry . Spokesman Kim Min-seok called the launches an 'armed protest ' against the South Korea-U.S. drills and a challenge to peace on the Korean Peninsula . UN resolutions prohibit any ballistic missile test by North Korea , and Mr Kim said Pyongyang appeared intent on triggering a 'security crisis ' . 'We will respond sternly and strongly to any provocation , ' he added . A statement carried by North Korea 's state-run news agency said : 'The situation on the Korean peninsula is again inching close to the brink of a war . Anger : Protesters gathered today near the U.S. Embassy in the South Korean capital Seoul . Uncompromising : North Korean leader Kim Jong Un has taken an aggressive stance against the West . 'The only means to cope with the aggression and war by the U.S. imperialists and their followers is neither dialogue nor peace . They should be dealt with only by merciless strikes . ' Officials in the North Korean capital Pyongyang claim the drills are 'intolerable aggression ' and preparation for an invasion - but South Korea says they are simply routine exercises . The largest element of the two drills that began today is Foal Eagle , an eight-week exercise involving air , ground and naval field training , with around 200,000 Korean and 3,700 US troops . The other is a week-long , largely computer-simulated joint drill called Key Resolve . Around 28,500 American soldiers are deployed in South Korea as deterrence against potential aggression from the North . North Korea has threatened attacks , including nuclear strikes , on the U.S. before , although it has never demonstrated its missiles could reach the U.S. mainland . During the 2013 drills , tension rose amid North Korean rhetoric that included vows of nuclear strikes on Washington and Seoul . North Korea has carried out three nuclear tests - in 2006 , 2009 and 2013 . In January , the North offered a moratorium on further tests if this year 's joint drills were cancelled - a proposal rejected by Washington as an 'implicit threat ' to carry out a fourth atomic detonation . Peace talks : There were hopes of the third summit between the Koreas since 1953 , but the prospect is dim . Threats : Protesters outside the embassy . People floating anti-Pyongyang flyers by balloon could be targeted . Jeung Young-Tae , an analyst at the Korea Institute for National Unification in Seoul , said Pyongyang was unlikely to conduct a fourth test just to protest against the exercises . 'Nuclear tests carry more significance than that , ' he said . 'On the other hand , there is the chance of a mid- or long-range missile test . ' I would say that a demonstration that it could deliver a nuclear warhead would be more threatening to the world than an actual nuclear test ' . A new research report by U.S. experts published last week estimated that North Korea could be on track to have an arsenal of 100 nuclear weapons by 2020 . In a further sign of rising tensions , North Korean state-run website Uriminzokkiri warned today of a fierce response to any attempt by South Korean activists to float anti-Pyongyang leaflets across the border by balloon . 'The response might not just be a few shots of gunfire but cannons or missiles , ' the website said . The two Koreas floated the possibility earlier this year of holding what would be the third summit between their leaders since the countries were divided 70 years ago . It is not certain whether the meeting will take place because the two countries disagree on terms .
Two short-range missiles fired into the sea off the regime 's east coast . The first missile was launched from a submarine, and it hit its target with great accuracy. Drills aided by the U.S. and military chiefs insist they are just defensive . But they raise tensions and in 2013 the North vowed nuclear retaliation .