The US has confirmed it will hold naval¹ exercises with South Korea, after a report blamed the North for the sinking of a Southern warship², officials say.

美国官员称，美国将于韩国联合举行海军演习，此前一份报告曾指责朝鲜击沉韩国一艘战舰。

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South Korea's president has vowed to punish those who carried out the attack

The Pentagon said the joint⁴ anti-submarine and other military exercises would start "in the near future".

South Korean President Lee Myung-bak earlier froze trade with Pyongyang, vowing⁵ to punish those who carried out the attack.

North Korea has said it will retaliate⁶（报复，回敬） for any action taken against it.

The country's main newspaper called the investigation⁷ an "intolerable, grave provocation⁸（激怒，挑衅） ".

'Unequivocal support'

South Korea has said it will refer the North to the UN Security Council in response to the sinking of the Cheonan - and the resulting death of 46 sailors - in March.

In a move endorsed⁹（支持，赞同） by the US, President Lee said in a televised address that Seoul would no longer tolerate "any provocative¹⁰ act by the North and will maintain a principle of proactive（有前瞻性的） deterrence¹¹（威慑，妨碍物） ".

Pentagon spokesman Bryan Whitman said the decision to start joint naval exercises was "a result of the findings of this recent incident".

Analysts¹² describe the joint exercises as a statement of US commitment to help Seoul rather than an attempt to intimidate¹³ Pyongyang.

US Secretary of State Hillary Clinton said earlier that her country was working hard to avoid an escalation¹⁴.

Japan said it was contemplating¹⁵（沉思，注视） its own sanctions on Pyongyang.

The North depends on South Korea and China for up to 80% of its trade and 35% of its GDP.

In 2009, inter-Korean trade stood at $1.68bn (£1.11bn) - 13% of the North's GDP.

The measures announced by South Korea included:
Stopping inter-Korean trade
Banning North Korean ships from using South Korean waterways or shortcuts¹⁶
Resuming "psychological warfare¹⁷（心理战） "
Referring the case to the UN Security Council

The BBC's John Sudworth in Seoul says the measures are as tough a response as the South could take short of military action.

The measures came less than a week after experts from the US, the UK, Australia and Sweden said in a report that a torpedo¹⁸（鱼雷，水雷） had hit the Cheonan.

They reported that parts of the torpedo retrieved¹⁹（取回，恢复） from the sea floor had lettering that matched a North Korean design.

Pyongyang denies any involvement in the sinking, calling the investigation a "fabrication（伪造，制造） " and threatening war if sanctions were imposed.

"If [South Korea] sets up new tools for psychological warfare such as loudspeakers and leaves slogans（口号，标语） for psychological warfare intact, ignoring our demands, we will directly aim and open fire to destroy them," a statement by the military said on Monday.

"More powerful physical strikes will be taken to eradicate²⁰（根除，消灭） the root of provocation if [South Korea] challenges to our fair response," said a commander, according to official news agency KCNA.