The next US president should put unprecedented pressure on North Korea to force it to choose between regime survival and nuclear weapons, a US expert said.

"US policy should focus on demonstrating that America is prepared to put at risk the one thing that the DPRK holds more dearly than its nuclear weapons -- the preservation of its regime -- in order to convince Pyongyang to end its pursuit of nuclear weapons," Evans Revere, a Korea expert who served as a principal deputy secretary of state, said in an article on the Brookings Institution website.

The argument came as some US experts have called increasingly for reopening negotiations with the North in order to curb its nuclear and missile development amid heightened fears in the wake of Pyongyang's fifth nuclear test last month that the regime is making real progress in its weapons programs.

Revere stressed that the North is unlikely to trade away its nuclear program for any incentives or rewards.

"Agreements with North Korea, starting with the Agreed Framework in 1994 and continuing through the so-called Leap Day agreement in 2012, were largely based on the expected attractiveness of incentives and rewards," the expert said.

"That hypothesis was worth testing early on, but experience demonstrated that incentives were of little value. As American negotiators and the international community eventually discovered, Pyongyang was not building nuclear weapons just to trade them away," he said.

The US and its allies and partners "should make North Korea choose between nuclear weapons and survival," he said.

"A more robust approach should aggressively build on current policy by going after the financial lifeblood of the North Korean regime in new ways," he said, adding that such measures include starving the regime of foreign currency, cutting Pyongyang off from the international financial and trading system, intensifying sanctions and squeezing its trading networks.

"Such an approach carries risks, including more complicated relations with China and some danger for South Korea. Importantly, however, America's South Korean ally agrees that now is the time to take risks in order to avoid a darker future and starker choices," he said.

Some experts have argued that the US should accept the North's demand for a peace treaty in exchange for a freeze on its nuclear program or to remove what Pyongyang claims is the "root cause" of its nuclear development, but Revere said that such thinking is "delusional."

"Buying into North Korea's proposal would seriously damage ties with the ROK, which is not prepared to negotiate a peace treaty with a nuclear-armed DPRK," he said. "Seoul would also not accept a peace treaty discussion in which it is not a central player. Peace on the Korean Peninsula can only be achieved if the two Koreas are at the table, and Pyongyang's proposal undermines this principle."

He stressed that the North's missile program is of no less concern than the nuclear program.

"North Korea's possession of reliable solid-fuel ballistic missiles would require the United States and its allies to consider a pre-emptive attack on the North's missile-related facilities to avoid being hit first," he said. (Yonhap)