North Korea makes nuclear threat after U.S. aircraft carrier arrives in South Korea

• Its arrival is "an undisguised military provocation driving the situation to irrevocable catastrophic circumstances," North Korea's state-run Korean Central News Agency (KCNA) said Friday, per Reuters.
• KCNA added that the aircraft carrier's arrival showed that the plan for a U.S. attack on North Korea had advanced.
• Pyongyang threatened Friday to respond to the U.S. aircraft carrier's arrival with its nuclear doctrine, which authorizes preemptive strikes, AP reported.

The big picture: North Korea has steadily developed its nuclear arsenal over the years and has adopted a more aggressive nuclear policy.

• A new law North Korea passed last year declared the country to be a nuclear weapons state and said it would preemptively strike the U.S. or South Korea if they attempted to remove North Korean leader Kim Jong-un from power.

Be smart: The U.S. and South Korea have regularly staged joint military drills in the region over vehement objections from North Korea.

• North Korea views these joint drills as rehearsals for war, and has conducted more than 100 missile tests since last year in response to joint U.S.-South Korea drills, per AP.

Go deeper: North Korea says it tested solid-fuel ICBM for first time