Seoul, South Korea (CNN) -- South Korea will "firmly" respond to future provocations from North Korea, South Korean President Lee Myung-bak said Monday, declaring that his nation "cannot remain patient" in the face of continued hostility from Pyongyang. "Fellow citizens, at this point, actions are more important than words," Lee said in a televised address Monday morning. "Please have trust in the government and the military and support us." The divided peninsula -- tense at the best of times -- has been near the boiling point since Tuesday, when four people died in a North Korean artillery barrage that targeted the South Korean island of Yeonpyeong. Lee called that attack an "inhuman crime" that followed decades of previous attacks from North Korea, including the sinking of the South Korean warship Cheonan in March.
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NEW: Lee condemns last week's shelling as an "inhuman crime"
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NEW: "We cannot stay patient and be generous"
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South Korea will consider a Chinese call for emergency talks
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North Korea calls the military exercises a pretext for war and aggression
"It is difficult at this point to expect @placeholder to abandon its nuclear weapons or military adventurism," he said.