US Secretary of State Mike Pompeo arrived in Pyongyang to continue preparations for US President Donald Trump’s upcoming summit with North Korean leader Kim Jong Un.

Pompeo’s visit is intended to lay the groundwork for the historic summit between the two leaders. A South Korean government official said the date and location of the Trump-Kim summit will also likely be announced following Pompeo’s trip.

The former CIA director is hoping he would return to the US with three detained Americans. The release of the detainees is a central issue in the US. Pompeo said he hoped North Korea would “do the right thing” and release three Americans imprisoned in the country.