Foreign company adopting plan for US citizens in foreign country?

[Guest Bristol]

I have a foreign company located in a foreign country employing US citizens. The company owns a US company with few employees. My questions are: (1) Is it permissible for the foreign company to adopt a 401(k) or P/S plan for the US citizens who are working in the foreign country? (2) Should the US company adopt a plan and make the employees (who are US citizens) of the foreign company eligilbe? and (3)Is income earned while working for a foreign company in a foreign country eligible compensation?