North Korea fires sixth projectile in three days

North Korea fires sixth projectile in three days
South Korean soldiers patrol along a barbed-wire fence near the village of Panmunjom, on the border with North Korea. (Ahn Young-joon / Associated Press)

North Korea

continued firing short-range weapons over its own eastern waters Monday after a weekend of what it called “rocket launching tests” intended to bolster deterrence against enemy attack. South Korean officials were investigating exactly what it was that Pyongyang was testing.

North Korea regularly conducts short-range missile tests. Analysts say the recent launches appear to be weapons tests or an attempt to get U.S. and South Korean attention amid tentative signs of diplomacy after soaring tensions that followed U.N. sanctions aimed at a North Korean nuclear test in February.

The two projectiles fired by North Korea on Monday had similar trajectories as four

over the past two days, according to officials at Seoul's Defense Ministry and the

Joint Chiefs of Staff

. Officials were analyzing whether the projectiles were missiles or rockets fired from a large-caliber gun North Korea may be developing, the officials said on condition of anonymity, citing department rules.

Defense Ministry spokesman Kim Min-seok told reporters earlier Monday that

South Korea

is taking seriously whatever weapons North Korea develops because it could attack South Korea. He said artillery guns with a larger caliber will likely have more destructive power.

South Korea urged North Korea to behave responsibly; the United States said threats or provocations would only further deepen the North's international isolation.

North Korea's Committee for the Peaceful Reunification of Korea on Monday called South Korean and U.S. criticism an “intolerable challenge” that is deepening tension. It said it conducted “rocket launching tests” on Saturday and Sunday as part of drills to bolster deterrence against what it calls U.S. and South Korean plots to launch nuclear strikes against North Korea. It didn't comment on Monday's firing.

North Korea has a variety of missiles, but Seoul and Washington don't believe the country has mastered the technology needed to make nuclear warheads small and light enough to be placed on a missile capable of reaching the U.S.

The Korean Peninsula officially remains in a state of war because the 1950-53

Korean War

ended with an armistice, not a peace treaty.