WASHINGTON -- Senior US officials have assured South Korea that military options against North Korea are a last resort, Seoul's top envoy to Washington said Monday.

Ambassador Ahn Ho-young told a National Assembly delegation that the message has been sent "consistently and convincingly."

"Responsible government officials in the US note that while all options are on the table, there are many things that can be done before taking up military options," he said during a parliamentary audit of the embassy.

Tensions have heightened over North Korea's nuclear weapons and ballistic missile programs, and the exchange of bellicose rhetoric between US President Donald Trump and the North Korean leadership has sparked fears of a war on the peninsula.

"The goal of the Trump administration's sanctions and pressure campaign is ultimately a peaceful solution to the North Korean problem," Ahn said. " Whether it's Defense Secretary James Mattis or Secretary of State Rex Tillerson, they all say the same thing."

The ambassador rejected speculation of a rift in the South Korea-US alliance on the North Korea issue, saying the US does not view the bilateral relationship from one angle only.

He also vowed to step up pressure on North Korea together with the United States and do his utmost to draw Pyongyang to denuclearization talks.

On Trump's visit to South Korea next month, Ahn said the White House is still in the process of allocating the president's time among South Korea, Japan and China.

The White House announced earlier in the day that Trump will hold talks with President Moon Jae-in on Nov. 7 but did not specify when he plans to arrive in Seoul.

Critics warn that North Korea will downplay the South Korea-US alliance should Trump spend more time in Japan. (Yonhap)