America doesn't actually have troops on the ground in Yemen, but Trump decided to veto the resolution against the genocidal war anyway. So who knows how long we'll be involved in that disaster.

Almost completely ignored is our rapidly expanding war in Somalia.

This week President Donald Trump signed an executive order extending a presidential declaration of a national emergency concerning Somalia for another year, calling the Islamist insurgency plaguing that country an "unusual and extraordinary threat" to the US.
...
For nearly two years, a small team of US Special Operations forces has been embedded with the Somali National Army, assisting in the fight against the militant group Al-Shabaab. As well as advising on airstrikes and ground assaults, the Navy SEAL-led team's primary task is to train and build Somalia its own elite light infantry force.
Named Danab, which in Somali means lightning, the force currently numbers only about 500 soldiers, too few to carry out operations in a country with a coastline almost as long as the east coast of the US. The plan, US defense officials say, is to eventually build Danab into a force of 3,000 soldiers capable of clearing militants from villages and towns across Somalia.
..."We think it's going to take approximately seven years for the Somalis to absorb all of these forces," a defense official familiar with the US counterterrorism strategy in Somalia told CNN.

US military advisers have been in Somalia since at least 2013. So 7 more years of build-up is planned, and that's if everything goes as planned. That doesn't take into account a final exit.
That would make it a 13 year war that is getting exactly zero discussion.

Something else getting almost zero discussion is our 18-year long war in Afghanistan, where three American soldiers were blown up just this week.
It seems that some effort is being put into ending this war.

All American troops would withdraw from Afghanistan over the next three to five years under a new Pentagon plan being offered in peace negotiations that could lead to a government in Kabul that shares power with the Taliban.

That means a 23-year long war...if the Taliban agrees.