WASHINGTON -- South Korea and the United States are set to hold back-to-back meetings in Washington this week to address the growing challenge posed by North Korea's nuclear and ballistic missile programs.

South Korean Vice Foreign Minister Lim Sung-nam and US Deputy Secretary of State John Sullivan are scheduled to meet Monday at a time of heightened concern over North Korea's ballistic missile capability.

The meeting will precede talks between South Korean Defense Minister Song Young-moo and US Defense Secretary Jim Mattis at the Pentagon on Wednesday.

Pyongyang tested two intercontinental ballistic missiles in July, leading many officials and analysts to believe it will soon be able to deliver a nuclear weapon to the US mainland.

Lim and Sullivan are expected to coordinate the allies' response to North Korean provocations and craft a way forward in dealing with the regime in Pyongyang.

Both Seoul and Washington have recently signaled a willingness to hold talks with Pyongyang to ease tensions and ultimately denuclearize the recalcitrant regime.

But Pyongyang has so far scoffed at the offers by increasing its bellicose rhetoric and launching three short-range missiles into waters between the Korean Peninsula and Japan on Saturday.

The diplomats are expected to discuss Seoul's request to revise a bilateral missile guideline that limits the range and payload of South Korea's ballistic missiles to 800 kilometers and 500 kilograms, respectively. With the rising threat from North Korea, South Korea wants to double the payload to 1 ton.

Wednesday's meeting between Song and Mattis is anticipated to additionally deal with the ongoing deployment of a US missile defense system to South Korea.

The Terminal High Altitude Area Defense system, or THAAD, has been operational in the southeastern county of Seongju since May, but with four launchers yet to be installed.

The South Korean government has been conducting a study to ensure the battery will not pose a health or environmental risk. (Yonhap)