Geopolitical deal reached over controversial Nord Stream 2 pipeline
The nearly completed 1,230km (764 miles) pipeline under the Baltic Sea will double Russian gas exports to Germany, Reuters reported.
US official Victoria Nuland said it was "a bad pipeline". Ukraine says the Nord Stream 2 pipeline threatens its security.
The country has been fighting Russian-backed separatists in the east since 2014. Russia also annexed the Crimea peninsula from Ukraine in 2014.
Ukraine also stands to lose about $3billion (£2.5 billion) a year in gas transit fees.
Poland is also opposing the pipeline, which runs from Vyborg in Russia under the Baltic Sea to Lubmin in Germany. Poland says the $10 billion (8.5 billion) project threatens the security of central and eastern Europe.
Russia denies this and describes the project as commercially beneficial for all involved.
Under the terms of the US-German deal, Ukraine will get $50 million (€42.4 million) in green energy technology credits and a guarantee of repayment for gas transit fees it will lose by being bypassed by the pipeline through 2024, according to the Associated Press.
The new pipeline will have the capacity of 55 billion cubic metres of gas per year to Europe.