The US military is scaling back an annual exercise with South Korea next month and will not deploy an aircraft carrier or fly strategic bombers for the drill, officials said Tuesday.

Last year Washington put on a show of military might for the exercise in response to saber-rattling by North Korea. But the United States is adopting a lower profile this time around, apparently due to some conciliatory steps by Pyongyang.

"There is no carrier involvement in exercise Key Resolve this year," a US defense official, who spoke on condition of anonymity, told AFP.

In addition, there were no plans to send out nuclear-capable bombers as in last year's drill, the official said.

"Every year the scenario is slightly different," said a second official, who also asked not to be named.

The two officials acknowledged that the United States tends to calibrate what ships and aircraft are featured in drills partly in response to North Korea's behavior.

Last year, in the months leading up to annual exercises Key Resolve and Foal Eagle, Pyongyang -- angered over UN sanctions -- stirred up tensions on the Korean peninsula with talk of a new war and threats to cancel the 1953 armistice agreement.

In response, the US military sent out B-52 bombers and B-2 stealth bombers for the exercises, as well as an attack submarine and two F-22 radar-evading fighter jets.

Word of a scaled back exercise follows a series of apparently conciliatory gestures made by North Korea in recent weeks, including calls to end all military hostilities.

Although there will be no American aircraft carrier or nuclear bombers for the exercises that start next month, South Korea said it would carry out a live fire drill on Tuesday near the disputed sea border with North Korea.

The North has warned of "grave consequences" if the live fire exercise goes ahead, and it has tended to view Seoul's joint drills with the United States as provocative preparations for an invasion.

Key Resolve is supposed to ensure "readiness" to defend South Korea and involves top military commands. The Foal Eagle event focuses on field training.

Last year, the Pentagon had about 2,100 troops take part in the Key Resolve exercise but officials did not say how many would take part this year.

South Korea hosts about 28,500 US soldiers and has a defense treaty with the United States.