SEOUL, South Korea - North Korea ordered its armed forces on standby and warned Monday it will retaliate against anyone seeking to block its planned satellite launch, which many fear will disguise a missile test.

The threat was the North's latest attempt to escalate tensions on the divided peninsula and a strong sign that the communist nation intends to push ahead with the launch despite mounting international pressure to drop the plan. Analysts say Pyongyang is trying to grab President Barack Obama's attention as his administration formulates its North Korea policy.

Monday's warning came hours before United States and South Korea kicked off annual war games involving tens of thousands of troops, which the communist nation has condemned as preparations for an invasion.

The joint drills across South Korea began as concerns mounted that North Korea could be gearing up to test-fire a long-range missile capable of reaching U.S. territory. North Korea says it plans to launch a communications satellite, but neighbouring governments believe it is a cover for a missile test.

Analysts have said a launch could come late this month or in early April when the North's new legislature, chosen in Sunday's election, is expected to convene its first meeting to confirm Kim Jong Il as leader.

American and Japanese officials have suggested they could shoot down a North Korean missile if necessary.

"If the enemies recklessly opt for intercepting our satellite, our revolutionary armed forces will launch without hesitation a just retaliatory strike operation not only against all the interceptor means involved but against the strongholds" of the U.S., Japan and South Korea, the general staff of the North's military said in a statement.

"Shooting our satellite for peaceful purposes will precisely mean a war," said the statement, carried by Pyongyang's official Korean Central News Agency.

The North's military ordered all personnel to "be fully combat ready" so that they could "deal merciless retaliatory blows" at the enemy, KCNA said in a separate dispatch.

North Korea also said it would cut off a military hot line with the South during the 12-day exercises, leaving the sides without any means of communication, triggering fears that even an accidental skirmish could develop into a battle as the sides have no way of contacting each other.

The two sides have used the hot line to exchange information about the crossing of goods and people through the industrial North Korean border city of Kaesong. Its suspension could halt traffic and strand about 570 South Koreans staying in the zone.

In Seoul, the new U.S. special envoy on Pyongyang met with South Korean Defence Minister Lee Sang-hee on Monday to discuss the tensions. Stephen W. Bosworth is scheduled to hold a series of meetings with President Lee Myung-bak and other senior officials later in the day.

Bosworth has urged Pyongyang to refrain from firing a missile, stop threatening neighbours, and defuse tensions through dialogue. The envoy arrived in Seoul on Saturday as part of an Asian tour that has already taken him to China and Japan.

The United States and South Korea have conducted annual military exercises a few times a year for decades, and Pyongyang has routinely condemned them as rehearsals for invasion.

The North had stepped up its war rhetoric in the run-up to the drills that began Monday. It has threatened South Korean passenger planes flying near its airspace, claiming the manoeuvres pose grave threats to its security.

Seoul and Washington have repeatedly said the drills, which involve its 26,000 military personnel in South Korea, an unspecified number of southern soldiers and a U.S. aircraft carrier, are purely defensive, and the allies do not have any intention of attacking the North.