Mill discipline and supply issues have brought US steel sheet prices up, but those prices are anything but secure, market sources told Platts Thursday.

"The mills timed [the increase] well," said one service center executive. "I don't think it will last terribly long, probably a little over a month, six weeks or so. A month from now the lead times will likely come back in and then we will see who holds the line. If you are buying now, though, you are paying their prices."

He added that lead times are currently getting a boost due to several mills dealing with outages and heavy backlogs, particularly mills producing cold-rolled coil.

Imports could also weigh heavily on pricing in the near-term, said one Western service center executive. The executive was offered Midwest hot-rolled at $650/st, but turned the deal down in favor of imported material.

"Imports are definitely attractive," he said. "I've got my fair share booked."

One mill source said many buyers were on the fence when the increase hit, and they bought immediately rather than face the new prices. Other market sources, however, have recently said that their respective mills did not offer the usual grace period with this increase and instead implemented full or partial increases the very next day.

The lone saving grace for elevated prices seems to be a general improvement in raw demand, said one end-user, who reported better industrial and non-residential construction orders concurrent with gentler weather.

"We're getting busy," the source said. "It's hard to say if it's pent-up demand or what it is right now, but we're happy for it and hopefully it will continue."

Platts maintained its hot-rolled assessment at $650-660/st and its cold-rolled assessment at $780-790/st, normalized to a Midwest (Indiana) ex-works basis.