Spanish Prime Minister Mariano Rajoy demanded on Wednesday that the Catalan regional government clarify if it considered itself independent or not following a speech by Catalan President Carles Puigdemont on Tuesday night.

This requirement is a necessary step before triggering Article 155 of the constitution, which would allow Madrid to suspend the region’s political autonomy.

Under that article, the central government could take control of the governance of a region, a never-before used provision that has been referred to as the “nuclear option”.

“The cabinet has agreed this morning to formally request the Catalan government to confirm whether it has declared the independence of Catalonia, regardless of the deliberate confusion created over its implementation,” Rajoy said in a televised address after a cabinet meeting to consider the government’s response.

Without giving a specific deadline for the Catalan government to reply, Rajoy said: “The answer from the Catalan president will determine future events, in the next few days.”

“The government wants to offer certainty to Spaniards, especially Catalans, it wants to avoid the confusion that has been generated by Catalan authorities.”

The premier’s move could deepen the confrontation between Madrid and Catalonia but it also signals a way out of Spain’s biggest political crisis since a failed military coup in 1981.

The prime minister would be likely to call a snap regional election after activating the constitutional mechanism allowing him to do so.

Puigdemont made a symbolic declaration of independence from Spain on Tuesday night but then immediately suspended it and called for talks with the Madrid government.

It is not yet clear if and when the Catalan government would answer Madrid’s call, but it now faces a conundrum, political analysts say.

If Puigdemont says he did declare independence, the government would likely trigger Article 155. If he says he did not declare it, then far-left party CUP would likely withdraw its support to his minority government.

“Rajoy has two objectives: if Puigdemont remains ambiguous, the pro-independence movement will get more fragmented; if Puigdemont insists on defending independence then Rajoy will be able to apply Article 155,” said Antonio Barroso, deputy director of London-based research firm Teneo Intelligence.

“Either way Rajoy’s aim would be to first restore the rule of law in Catalonia and this could at some point lead to early elections in the region”.

Puigdemont had been widely expected to unilaterally declare Catalonia’s independence on Tuesday after the Catalan government said 90 percent of Catalans had voted for a breakaway in an October 1 referendum that Spain had declared illegal and which most opponents of independence boycotted.

Madrid responded angrily to Puigdemont’s speech, saying the Catalan government could not act on the results of the referendum.

“Neither Mr. Puigdemont nor anyone else can claim, without returning to legality and democracy, to impose mediation… Dialogue between democrats takes place within the law,” Deputy Prime Minister Soraya Saenz de Santamaria said.

Invoking Article 155 would make prospects of a negotiated solution to the Catalonia crisis even more remote.

The article allows the central government to take some or total control of any of its 17 regions if they do not comply with their legal obligations. This would begin with a Cabinet meeting and a warning to the regional government to fall into line. Then, the Senate could be called to approve the measure.

A spokesman for the Catalan government said earlier on Wednesday that if Madrid went down this road, it would press ahead with independence.

“We have given up absolutely nothing…We have taken a time out…which doesn’t mean a step backwards, or a renunciation or anything like that,” Catalan government spokesman Jordi Turull told Catalunya Radio.

Socialist opposition leader Pedro Sanchez said he would back Rajoy if he had to activate Article 155 and said he had agreed with the prime minister to open a constitutional reform within six months to discuss how Catalonia could fit better in Spain.

It was not clear how the Catalan government would respond to the offer.

About 2.3 million Catalans — or 43 percent of the electorate in the northeastern region — voted in the referendum. Regional authorities say 90 percent were in favor and declared the results valid. Those who opposed the referendum had said they would boycott the vote.