Five U.S. Navy ships have arrived in South Korea to take part in an ongoing annual military exercise between the allies, the Combined Forces Command said Thursday.

On Monday, Seoul and Washington kicked off the field training exercise Foal Eagle as part of efforts to improve the combined forces' operations and combat capabilities to deter threats from North Korea. The drill involves 200,000 South Korean and 3,700 American troops and is scheduled to run until April 24.

"Five Navy ships from the U.S. 7th Fleet arrived at local naval ports one after another," a CFC official said. "The warships will provide an opportunity for Navy sailors of the two countries to cooperate on security."

According to the CFC, two 9,200-ton destroyers, the USS Michael Murphy and the USS John S. McCain, and a 3,000-ton battleship, the USS Fort Worth, entered the port of Pyeongtaek on the west coast, while another 9,200-ton destroyer, the USS Lassen, and a 3,000-ton salvation ship, the USS Salvo, arrived at Donghae and Jinhae on the east and south coasts, respectively.

This marks the first time that a U.S. littoral combat ship is taking part in the Foal Eagle drill.

"The U.S warships will conduct exercises involving naval firing, the movement of war vessels and logistics support together with the South Korean Navy," the CFC official said. "The number of American warships taking part in this year's Foal Eagle drill is similar to that in an average year."

Also on Monday, South Korea and the U.S. began the Key Resolve military exercise, which mobilizes about 10,000 South Korean and 8,600 American troops and is scheduled to end on March 13.

Meanwhile, the first part of the Key Resolve exercise finished on Thursday morning, one day ahead of schedule, affected by a knife attack on U.S. Ambassador to Seoul Mark Lippert earlier in the day, according to South Korean government sources.

A 55-year-old man attacked Lippert at a breakfast function in central Seoul where he was having breakfast before giving a lecture. Lippert was listed in stable condition after having cuts on his face and wrist stitched at a Seoul hospital.

"The schedule was inevitably changed because Gen. Curtis M. Scaparrotti, the CFC commander, had to take part in administrative work on the U.S. side to cope with the incident," one of the sources said. (Yonhap)