The United States Embassy today praised Malaysia's professionalism in handling the investigation into the murder of Kim Jong Nam in Kuala Lumpur last month.

United States Assistant Secretary of State Daniel Russel said Malaysia acted swiftly within the proper channel in the case involving the estranged half brother of North Korean leader Kim Jong Un.

"I want to express our respect and admiration for the professionalism of the Malaysian law enforcement authorities who conducted an impressive investigation and worked from the facts in a quick and professional and sophisticated manner.

"The hijacking of the territory of a country by a foreign power for the purpose of murder – for the purpose of political assassination – is reprehensible and my sympathies go to Malaysia on that account," he said in a statement.

At the same time, Russel also expressed regret over the current diplomatic contretemps between Malaysia and North Korea.

READ: Timeline - The unravelling of ties between North Korea and Malaysia

However, he said, he fully understands the actions taken by Prime Minister Datuk Seri Najib Razak and Foreign Minister Datuk Seri Anifah Aman in deciding to exercise their right under the Vienna Convention.

He was referring to the declaration of persona non grata on a diplomat who refuses to cooperate with a legitimate and lawful request by the host government and subsequently the order of expulsion issued.

"I also share and understand the concerns of the Malaysian government with respect to the welfare of its citizens currently in the Democratic People's Republic of Korea," he added.

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Russel also said the United States has itself some unfortunate examples of American citizens detained in North Korea.

"There are some as I speak. I can only hope that there is a quick and satisfactory resolution of the issues between Malaysia and the DPRK.”