▶ Watch Video: Veterans react to fall of Afghanistan to Taliban

The U.S. Defense Department on Wednesday circulated a list of mental health resources available for veterans amid the Taliban’s takeover of Afghanistan. Although the Defense Department did not mention Afghanistan by name, the information came as U.S. forces leave the country and the capital falls to the Taliban after a 20-year war.

“You are not alone,” the Defense Department wrote. “Remember that what is happening now does not minimize or negate the experiences of all who served overseas. Countless service members answered the call of duty and did what was asked of them. Service is never for naught. Think about the times when valor and courage changed lives for the better. Focus on the present and what feels meaningful to you in this moment. Our veterans served honorably and completed missions as required and as necessary – protecting our freedoms and we are forever grateful for their service.”

While the U.S. presence in Afghanistan has been significantly reduced in recent years, nearly 800,000 service members served at least one deployment since the war started in 2001. And over 2,400 have died in action, leaving behind countless friends and family members.  

The Commandant and the Sergeant Major of the Marine Corps sent a letter to Marines saying “some of you may be struggling with a simple question ‘was it all worth it?'” 

A tattoo on the back of U.S. Army Sgt. James Wilkes of Rochester, New York, is seen through his torn shirt after a foot patrol with 1st Platoon, Charlie Company, 2nd Battalion, 1st Infantry Regiment, of the 5th Styker Brigade on May 8, 2010, in Afghanistan’s Kandahar province. The full tattoo reads, “Sacrifice. Without fear there is no courage.”

Julie Jacobson / AP

“You never, ever gave up,” the letter said. “You lived with purpose, with intention. Whether you realize it or not, you set an example for subsequent generations of Marines — and Americans — by living our core values of honor, courage and commitment. Was it worth it? Yes. Does it still hurt? Yes.” 

The U.S. Army Chief of Staff General James McConville in a letter said, “In the next few days and weeks, I’d ask that you check in on your teammates as well as our Soldiers for Life, who may be struggling with the unfolding events. We will continue to move forward and serve our Nation with honor and dignity.” 

Juan Dominguez, who was a Marine lance corporal when he was sent to the Taliban heartland of Helmand Province in 2010, told CBS News’ David Martin that he was on “the verge of breaking down crying because this is just like we gave so much and just like that it’s wiped out.”

The Department of Veterans Affairs sent a letter Monday to nine million people to remind veterans they’re not alone and offer resources like the Veteran Crisis Hotline. The department told CBS News the hotline has seen an increase in calls since Kabul fell Sunday. 

Defense Secretary Lloyd Austin said Wednesday that the situation in Afghanistan is “personal” to him as someone who fought — and led — in the war.

“For the military, these are difficult days for those who lost loved ones in Afghanistan and those who carry the wounds of war,” Austin said. “Let me say to the families and loved ones: We stand as one to honor those we’ve lost. I’m hearing strong views on all sides on this issue – what’s important is each of us will work our way through this in our own way. Respect that.”

The Defense Department has compiled a list of resources for mental health services for veterans and their families that is available here

If you or someone you know might be at risk of suicide, there is help. Call the National Suicide Prevention Lifeline at 800-273-8255, text a crisis counselor at 741741 or visit suicidepreventionlifeline.org.