  We consider intuitionistic variants of linear temporal logic with `next',
`until' and `release' based on expanding posets: partial orders equipped with
an order-preserving transition function. This class of structures gives rise to
a logic which we denote $\iltl$, and by imposing additional constraints we
obtain the logics $\itlb$ of persistent posets and $\itlht$ of here-and-there
temporal logic, both of which have been considered in the literature. We prove
that $\iltl$ has the effective finite model property and hence is decidable,
while $\itlb$ does not have the finite model property. We also introduce
notions of bounded bisimulations for these logics and use them to show that the
`until' and `release' operators are not definable in terms of each other, even
over the class of persistent posets.
