Think military advisors, the Gulf of Tonkin Resolution and mission creep.
Typically, American hubris has meant overreaching, and "mission creep" has historically been synonymous with disaster.
But “Iran likely has its own limits in terms of mission creep in Syria,” says Vira.
the gradual process by which a campaign or mission's objectives change over time, esp. with undesirable consequences
The only way to explain our involvement in Iraq is mission creep.