U.S. and Moldovan military forces have begun joint military exercises that are scheduled to last for more than two weeks.
About 200 U.S. troops in an armored column entered Moldova from Romania at dawn on May 3, a day after Defense Ministry officials in Romania said they would cross the border.
The U.S. troops crossed into central Moldova at the Sculeni checkpoint and passed through the town of Falesti before heading southeast on the M14 highway to the town of Negresti, about 20 kilometers northwest of the capital, Chisinau.
Code-named Dragon Pioneer 2016, the joint exercises are scheduled to continue until May 20.
The Socialist Party of Moldova, a pro-Russian opposition party, had called for demonstrators to block the route.
But fewer than a dozen protesters joined that protest and the U.S. troops advanced to the site of the exercises near Negresti without hindrance.
Opposition parties have called for a protest in Chisinau during the May 9 Victory Day celebrations, when the U.S. troops were scheduled to make an appearance with their armored personnel carriers in the Moldovan capital.
The exhibition of U.S. armored personnel carriers in Chisinau is one of the events in Moldova marking the 71st anniversary of the allied victory against Nazi Germany that brought World War II to an end in Europe.
Socialist Party leader Igor Dodon called the exercises a "military occupation."
Moldovan Defense Minister Anatol Salaru responded to Dodon's criticism by saying that "Dodon's cavalry have forgotten to leave" Moldova since the arrival of Soviet forces there in 1944.
His remarks referred to the continuing presence of Russian troops in Moldova's eastern breakaway region of Transdniester.
Russia has maintained its troop presence of about 1,500 soldiers in Transdniester since a cease-fire deal brought an end to the separatist conflict there in 1992.
About 380 of those Russian soldiers are deployed under an international l peacekeeping mandate.
The remainder are soldiers from Russia's 14th Guards Army.
Moldova joined NATO's Partnership for Peace program in 1994.