South Korean President Lee Myung-bak says his government is nearing a deal with the United States to expand the range of its ballistic missiles to counter the threat from North Korea.

President Lee told reporters in comments published Thursday he believes a deal will be reached in the “near future” to extend the current 300-kilometer range, which was set by a 2001 agreement with the United States.

Mr. Lee said that deal was based on the assumption that any fighting between the two Koreas would be around the demilitarized zone separating the two countries.

But he said increasingly advanced North Korean missiles are now capable of reaching as far as Jeju Island, located well off the southern coast of South Korea. He said Washington and Seoul agree on the need for a “new security environment.”

His comments come amid regional tension over North Korea's recently announced plan to launch a satellite into orbit in mid-April – a move that many say violates an agreement to halt nuclear activity and missile tests.

Mr. Lee said the launch is “another litmus test of the new regime” of North Korea's new leader, Kim Jong Un.

South Korea has described the launch as a “grave provocation,” saying it is a cover for the testing of a long-range missile capable of carrying a nuclear weapon. The U.S., Russia, South Korea and Japan have condemned the planned launch, which North Korea says is for “peaceful scientific purposes.”

About 50 world leaders are set to gather in Seoul next week for a high-profile nuclear security summit. While officials say the North Korean nuclear issue is likely to be discussed at the two-day summit, North Korea has warned that any resolution concerning its nuclear program will be considered an “act of war.”