The honeymoon between President Moon Jae-in and the opposition -- if there was any -- is over, with the two sides bracing for the first round of contention since Moon took office a little over three weeks ago.

Chung Woo-taik, floor leader of the main opposition Liberty Korea Party, declared an end to the short-lived bedding-in period. He also said that his party would not accept the president’s proposal to form a policy consultative body consisting of the government and ruling and opposition parties.

On the surface, Chung and other opposition leaders cited the fact that Moon and the ruling party did not seek their consent for the parliamentary confirmation of Prime Minister Lee Nak-yon. They criticized Moon for not making a clear public apology for Lee’s ethical problems that had surfaced during the confirmation process. But there are more good reasons for the opposition to form a battle line.

Before and after taking office, Moon emphasized “cooperative governance,” stressing that the rival parties should refrain from confrontational politics and instead pursue dialogue and compromise in major state affairs.

Moon fostered a cooperative mood by paying a personal visit to the four opposition parties one day after he took office. He also invited floor leaders of major parties to a Blue House luncheon, in which he proposed the trilateral body of government, ruling and opposition parties.

But some of what Moon did his first weeks as president ran counter to what he said he would do. The liberal president made one move after another that provoked the opposition and conservatives as a whole.

What irritated the president’s critics included the unilateral reinstatement of an activist song in the ceremony marking the 1980 civil uprising in Gwangju, the revocation of state-authored history textbooks and an investigation into the four-rivers project pushed by the Lee Myung-bak administration.

On top of these came some blunders, which emboldened the opposition to raise its voices against the new administration, which had been gaining 80 percent-plus public approval ratings.

Most of all, Moon is repeating the same mistake as his predecessors did: Nominating people with ethical problems to senior government positions. This become more controversial because during the election campaign, Moon promised to set strict ethical standards for presidential appointees.

As it turned out, Lee and other major nominees, including those for such key posts as the foreign minister and the antitrust chief, were found to have breached the bar set by Moon.

His spokesman apologized for the candidates’ ethical lapses -- the most common one is registration of false residential addresses -- but Moon ignored the opposition demand that he personally apologize and clarify his position on whether to keep upholding the standards or not.

The controversy over the launchers for the US antimissile system deployed here is fueling the already growing opposition skepticism about the Moon administration’s commitment to national security.

It has yet to be verified whether Defense Ministry officials intentionally tried to keep Moon in the dark about the arrival from the US of the launchers for the Terminal High Altitude Area Defense System, and the opposition has enough grounds to believe that Moon is using the issue for political purposes.

One purpose could be taming bureaucrats who the liberal government thinks have become accustomed to serving the two successive conservative governments over the past nine years.

Moon’s top aide Kim Jin-pyo has already expressed frustration with tackling the civil service and the family-controlled chaebol, warning them not to “resist” reforms pushed by the Moon administration.

This is the same man who, taking office as head of the presidential panel drawing up major policy road maps for the new government, said the panel members should not behave as “occupation forces” in dealing with the civil service.

This kind of us vs. them mentality is the last thing that should be espoused by an administration which seeks the kind of cooperative governance this nation has never seen before.