BERLIN (Reuters) - Greens want the next coalition government to push for the removal of all nuclear warheads stationed in Germany, a document seen by Reuters showed on Wednesday.

The discussion paper on defence and foreign policy did not mention the United States, which is believed to have 20 nuclear warheads at a military base in Buechel in western Germany, according to unofficial estimates.

Chancellor Angela Merkel is trying to secure a fourth term through an unlikely coalition with the ecologist Greens and pro-business Free Democrats (FDP) after her conservative bloc lost support to the far-right in an election in September.

NATO member Germany is not a nuclear power and in 2011 a Merkel-led government announced plans to shut all nuclear reactors by 2022 after the Fukushima disaster in Japan.

“Within NATO, we want to ensure that the remaining nuclear weapons in Germany are withdrawn and we want to suspend the modernization programme,” read a section in the document stating the Greens’ position.

Before leaving office former U.S. President Barack Obama announced plans to modernize nuclear bombs, delivery systems and laboratories. His successor, Donald Trump, has said he wants to strengthen and expand his country’s nuclear capability.

The conservatives, Greens and FDP are hoping to end exploratory discussions on Thursday and move on to proper negotiations on forming a government.

They remain divided on several key issues, including immigration, reforming the euro zone and climate policy.