In her New Year news conference Monday, President Park Geun-hye said the latest U.S. sanctions on North Korea for its alleged hack on Sony Pictures would not derail Seoul’s efforts to push for talks with Pyongyang. But it seems that her administration’s recent moves toward resuming inter-Korean dialogue are set to be moderated by a hardening U.S. stance against the North.

Speaking at a House committee hearing the day after Park’s news conference, a senior U.S. diplomat said the U.S. “is using the full range of tools at our disposal” to get the North to change its course and abide by its international obligations. Amb. Sung Kim, special representative for North Korea policy, said Washington would “apply pressure both multilaterally and unilaterally” to increase the cost to Pyongyang of its destructive policy choices.

Attending the same session, Assistant Treasury Secretary for Terrorist Financing Daniel Glaser said the U.S. would push for sanctions to cut the regime off from the international financial system.

Officials in Seoul and Washington say the allies are closely coordinating their stance on how to deal with the North. A U.S. State Department official said Wednesday there was no daylight between Seoul and Washington on efforts to improve inter-Korean ties. The official noted progress in inter-Korean dialogue could play an important role in bringing the North back to “authentic and credible” negotiations on dismantling its nuclear arsenal. South Korean officials have also expressed confidence that the alliance between Seoul and Washington is strong enough to smooth out possible differences in their approaches toward Pyongyang.

But the compatibility between inter-Korean dialogue and the allies’ coordination on the North’s denuclearization may be seriously tested if Seoul and Pyongyang make substantial headway in their talks. In her news conference, Park emphasized the North should show sincerity toward denuclearization, but attached no strings to holding talks with its leader Kim Jong-un. South Korea needs to reach unequivocal understanding with the U.S. on whether, when and to what degree to ease the blanket economic and trade sanctions it imposed on the North under the administration of Park’s predecessor Lee Myung-bak.

Pyongyang has recently given mixed signals about inter-Korean talks, while asking for contact with Washington regarding its offer to temporarily suspend nuclear tests in return for a halt to joint military exercises between South Korea and the U.S. Since Kim suggested in his Jan. 1 address that he was open to holding talks with Park, the North has remained silent on the South’s repeated calls for inter-Korean dialogue, putting forward a series of thorny preconditions.

Pyongyang seems to be attempting to drive a wedge between Seoul and Washington and secure concessions without abandoning its nuclear arms programs. But the impoverished and isolated regime will achieve nothing by sticking to this outmoded tactical calculation. The North now needs to decide on whether to engage in serious dialogue with the South, which might offer a way out of its deepening predicament ― but only after its ultimate intentions are made clear.