Yemeni Civil War: Qatar was part of the Saudi-led coalition that intervened in the Yemeni Civil War in 2015 against the Houthi rebels. Qatari involvement included airstrikes, ground troops, and financial support to anti-Houthi forces.
Libyan Civil War: Qatar initially supported the 2011 NATO-led military intervention in Libya against Muammar Gaddafi's regime. Later on, it backed various rebel groups during the subsequent Libyan Civil War.
Syrian Civil War: Qatar provided financial and logistical support to certain rebel groups fighting against the Syrian government in the Syrian Civil War, although its involvement was relatively limited compared to other regional actors.
These are the notable conflicts in which Qatar has been directly or indirectly involved in recent decades.