WASHINGTON -- It's the holidays, and millions of Americans are making their way to visit family and friends.And many of those travelers are military personnel returning home from their duty stations.But hundreds of thousands of military personnel will not be traveling. Based around the globe, they will continue to protect the United States.THREATS DON'T TAKE A HOLIDAYMany American service members must stay at their jobs, because threats don't take a holiday.According to the most recent statistics available at the Defense Manpower Data Center, there are about 1.3 million personnel on active duty, with about 476,000 in the Army; 323,000 Navy; 184,000 Marine Corps; 321,600 Air Force and 41,500 in the Coast Guard. There are 810,800 in the selected reserves.Service members serve on all seven continents -- there is one service member in Antarctica -- and on all the seas. Military personnel are in more than 170 countries.There are about 13,000 troops from all service branches in Afghanistan. They are working to train and advise Afghan forces and supply the fires needed to help defeat the Taliban and terror groups.There are 5,200 service members in Iraq and another 2,000 in Syria. They are working with Iraqi forces and the Syrian Democratic Forces to rid the region of the Islamic State of Iraq and Syria.There are roughly 28,000 service members in South Korea, deterring North Korean leader Kim Jong Un.Overall, there are more than 60,000 U.S. service members in the U.S. Central Command area of operations on shore and aboard ships.There are 710 U.S. troops in Kosovo.Djibouti -- on the Horn of Africa -- hosts 3,100 American service members, and there are 505 service members in Niger.There are 34,300 service members in Germany, 8,300 in the United Kingdom and 44,500 in Japan. Those troops' presence reassures allies and deters competitors.These are just some of areas where active duty personnel are deployed this holiday season. They are joined by National Guard and Reserve personnel.There are almost 20,000 National Guardsmen serving alongside their active duty brothers and sisters. They are operating far from their homes in some of the most dangerous areas on Earth.Guardsmen are also helping their fellow citizens more directly, with almost 5,000 battling wildfires in California or delivering supplies in Puerto Rico. And if the call comes on Christmas morning to help their fellow citizens, they will put down the coffee and put on the uniform.From its birth, the Navy has been an expeditionary force. Sailors will man their ships from the Persian Gulf to the Gulf of Mexico. Navy officials maintain that roughly a third of the Navy is deployed at any one time. By that measurement, it means more than 100,000 sailors and Marines are afloat on Christmas.Sailors are performing missions that cannot stop for the holidays. Christmas is just another day for sailors manning their posts aboard submarines with nuclear weapons. Sailors launching aircraft from the USS Theodore Roosevelt in the Persian Gulf may have time for Christmas services.The same holds true for Air Force missileers and airmen who will be in the silos, by the planes and in the command centers ensuring the nuclear system is ready, if needed.MONITORING CYBER, SPACEU.S. Cyber Command personnel will monitor the cyber world for threats, and service members will scan space to ensure those assets are not threatened.Even at all these far-flung areas, service members will take time to remember the holidays. Dining facilities do their best to ensure every service member has a great holiday meal. Centers work overtime to help service members contact loved ones back home. At some places, there will be sporting matches and perhaps the troops may get a bit more rack time.But this is the way it has always been. The military is always on duty and has been from Valley Forge in 1778 to Fredericksburg in 1862, from Bastogne in 1944 to Chosin in 1950, and from Linebacker 2 in 1972 to today.The bottom line is the U.S. military stands guard so the world can know -- or hope for -- peace.