The State Department, which represents the US in international affairs and foreign policy, has issued the advice amid escalating tensions with Kim Jong-un’s regime.
A US passport will no longer get you into North Korea, but a special validation is possible in rare cases.
The department’s first recommendation to travellers reads: “Draft a will and designate appropriate insurance beneficiaries and/or power of attorney”.
The second adds: “Discuss a plan with loved ones regarding care/custody of children, pets, property, belongings, non-liquid assets (collections, artwork, etc.), funeral wishes, etc.)
A State Department comment on its website reads: “The US government is unable to provide emergency services to US citizens in North Korea as it does not have diplomatic or consular reactions with North Korea.”
The advisory adds that the US has no diplomatic or consular presence in North Korea.
Swedish officials have also been bared from visiting detained US citizens in the past, the State Department has said.
Journalists and those with “compelling humanitarian considerations” like the Red Cross can apply for special validation to visit North Korea.
The US also advises travellers to ten other countries to plan a will before visiting.
They are Afghanistan, the Central African Republic, Iran, Iraq, Libya, Mali, Somalia, South Sudan, Syria and Yemen.
President Donald Trump announced that the US had designate North Korea as a state sponsor of terrorism in November last year.
It added the nation to a list that includes Iran, Sudan and Syria.
US college student Otto Warmbier was imprisoned in North Korea for more than a year and died days after he returned to the US in a coma.
Trump said: “North Korea has repeatedly supported acts of international terrorism including assassinations on foreign soil.
“This designation will impose further sanctions and penalties on North Korea and related persons.”
The State Department’s warning comes just weeks after Kim, while calling for improved relations with South Korea, threatened to strike the US with nuclear warheads.
He said: “The entire area of the US mainland is within our nuclear strike range.
“The United States can never start a war against me and our country.“