South Korean President Lee Myung-bak said Friday his country needs a stronger military to cope with threats from abroad, amid rising tension with its nuclear-armed neighbor, North Korea. "Only a strong military can deter outside aggression and protect the lives and safety of the people," Lee said in a message to navy personnel, according to the presidential Blue House. "Only a strong military can create a rich and powerful country and contribute to world peace and prosperity." Lee also said South Korea should bolster its naval power to "immediately repel" any threat and possible terrorist strike that could take place in South Korean waters. The message was delivered to sailors who returned home following their recent participation in multilateral naval training off Hawaii. Though Lee did not mention North Korea by name, his comments followed the communist country's sharp criticism this week over annual military drills conducted by South Korea and the United States. North Korea threatened to strengthen its "war deterrent" - a euphemism for its nuclear programs - calling the training a rehearsal to attack the communist country, a claim Seoul and Washington have consistently denied. On Thursday, Lee visited and inspected two underground bunkers south of Seoul where top South Korean and US military officers were commanding the annual computer-simulated training, called Ulchi Freedom Guardian. "There should not be a war again in this country," Lee said in one of the bunkers, according to a separate Blue House statement. "But if war breaks out, (South Korea and the US) should always have a readiness to end it by that night." North Korea suspended key government-level talks with South Korea after the conservative Lee assumed office in February on a pledge to take a tougher line with Pyongyang than his liberal predecessor, who favored dialogue and economic cooperation. Tensions spiked further after a North Korean soldier shot dead a South Korean tourist at a mountain resort last month, after she allegedly entered a restricted military area and ignored warnings to stop.