SEOUL, South Korea - The ballistic missiles that North Korea test-fired this weekend were likely capable of striking key government and military facilities in South Korea, a defense official said Sunday, amid growing concerns over Pyongyang's firepower.

North Korean state media did not mention the launches but boasted that the country's military could impose "merciless punishment" on those who provoke it.

Pyongyang launched seven missiles into waters off its east coast Saturday in a show of force that defied U.N. resolutions and drew international condemnation.

The missiles appear to have traveled about 250 miles (400 kilometers), meaning they could have reached almost any point in South Korea, an official at the South Korean Defense Ministry said on condition of anonymity, citing department policy.

The official said the exact details of the launches were still under investigation.

The launches on U.S. Independence Day appeared to be a poke at Washington as it moves to enforce U.N. as well as its own sanctions against the isolated regime for its May 25 nuclear test.

But Vice President Joe Biden indicated the U.S. would not be baited. He described the flurry of rockets as "attention-seeking behavior."

He added: "I don't want to give the attention."

North and South Korea, which fought a 1950-53 war, still face off across the world's most heavily fortified border. The United States, South Korea's key ally, has 28,500 troops stationed in the country as a deterrent.

‘Merciless punishment’
The North's main Rodong Sinmun newspaper said in a commentary that "our revolutionary forces have grown up today as the strong army that can impose merciless punishment against those who offend us," crediting the country's "military first" policy.

The commentary was carried Sunday by the official Korean Central News Agency.

Last month, the North threatened a "thousand-fold" military retaliation against the U.S. and its allies if provoked.