AVA- "If the United States reduces itself to a small contingent in Afghanistan there's no reason for us to continue the mission anymore," Kujat told the German Tagesspiegel newspaper on Thursday.
The former head of the Bundeswehr said it was "out of question" for German forces to remain in Afghanistan if they could not be given guaranteed protection and support.
Kujat, however, added that he expected other NATO members to increase contribution to make up for any US troop withdrawal.
Minister of State in the German Foreign Ministry Niels Annen also expressed frustration with the American announcement.
"We have noticed repeatedly that the Trump government does not particularly value close coordination with its allies. We're currently trying to reach clarity by speaking to our colleagues in Washington and Kabul," said Annen.
US President Donald Trump reportedly ordered the withdrawal of some 7,000 troops, half of the total number of American forces in the country, from Afghanistan last week.