  We review recent high-resolution CO observations of distant QSOs obtained at
the Very Large Array. The aim of these observations is to resolve the molecular
gas distribution in these extreme objects both spatially and in velocity space.
They provide unique information regarding the small-scale distribution, the
extent, and the brightness temperatures of the molecular gas in these early
systems. E.g., the structure and dynamics of the molecular gas may reveal
whether or not mergers can be the cause of the ongoing starburst activity. The
observations also allow for a first estimate of the dynamical gas mass.
Currently, only the VLA is able to obtain resolutions in CO of up to 0.15"
which is needed to resolve typical galactic structures of sizes ~1 kpc. We
present new high-resolution VLA imaging of high-z QSOs (BRI 1335-0417, APM
08279+5255 and J1148+5251). These observations pave the road to future ALMA
observations where resolutions of order 0.1'' will be obtained routinely.

Astrophysics