According to the US Citizenship and Immigration Services, since October 1, 2002, the USCIS has naturalized 102,266 foreign members of the military. In 2009, about 114,601 immigrants, or about 12% of the armed forces, were not US citizens. One hundred and nineteen foreign born military personnel were granted US citizenship posthumously in 2009.
As of late 2013, it has been estimated that about 5% of the US military is foreign born. The top five countries of origin for foreign-born US soldiers are the Philippines (22.8%), México (9.5%), Jamaica (4.7%), Korea (3.1%) and the Dominican Republic (2.5%) 
It was also estimated that about three percent of the US military veterans that were alive in 2012 were foreign born. 
Immigrants serving in the US Armed Forces have a rich tradition of service going as far back as the Revolutionary War.
During World War II, between July 1, 1940 and June 30, 1945, more than 300,000 foreign-born individuals were enlisted or inducted into the United State Army.  Of the 300,000 military personnel, over 109,000 were not United States citizens at the time of their enlistment.  Of these, about 19,000 were Mexican citizens that served in the US Army during World War II. About 77% of the Mexicans that entered the service, enlisted prior to obtaining US citizenship.
Mexicans were the second largest group of immigrants, after the Canadians, of the total number of immigrants who had not been naturalized at the time of entering the US Army in World War II. 
Many immigrants have died while serving. Many of them were not even US citizens at the time of their deaths.
One of the first to die during Operation Iraqi Freedom was Lance Cpl. José Gutierrez, from Guatemala who was killed in a tank battle in Iraq in March 2003. He was granted US citizenship posthumously.
The latest immigrant to fall, while serving in the US Armed Forces, is Cpl. Sara A. Medina, a 23-year Mexican-born US Marine who died in Nepal on May 12, 2015 while conducting earthquake relief operations. A combat photographer, Medina was engaged to be married later this year.
As you reflect upon those who have sacrificed their lives in service for the United States, take a moment to remember the many immigrants to the US, some not even citizens that have paid the ultimate price for the safety and security of the US.
1. Barry, Catherine N.; “New Americans in Our Nation’s Military – A Proud Tradition and Hopeful Future”; Center for American Progress, November 8, 2013
2. Miller, Watson B.; Commissioner of Immigration and Naturalization, “Foreign Born in the United States Army During World War II, with Special Reference to the Alien”; Department of Justice, Immigration and Naturalization Service Monthly Review Vol. VI, No 4.; October 1948