U.S. troops arrived in Turkmenistan in late 2001, following the events of September 11, 2001. Their presence was part of the broader military response to the War on Terror, particularly in neighboring Afghanistan. The troops were primarily there to support operations and provide logistical assistance.
2012
I don't think it says who was the first soldier to arrive in Europe in 1942 but the first US troops arrived in Northern Ireland on January 26 1942.
1908
As far as I know America has never arrived in Australia. American troops were stationed in Australia during WW2 because the Japanese bombed Darwin, and American tourists arrive in droves every year, but as a nation the US has never actually "arrived".
Mid-19th century.
In 2006.
1965
US Army Air Corps May 1942 in England
July 19 1885
2001.
On June 26, 1917, the first US troops arrived in France during World War I. Unfortunately, the soldiers arrived untrained, and lacking in both equipment and readiness to begin to fight on the western front.
Well before any US troops were sent to Vietnam. The Korean Conflict kicked off in 1950, and the ceasefire was signed in 1953 (although the conflict remains ongoing). The first American troops didn't arrive in Vietnam until 1954.