President Donald Trump claimed Monday that the United States would “save Billions of Dollars if the Democrats would give us the votes to build the Wall,” without explaining how his elusive border wall would create a savings bonanza.

Lawmakers are looking to avoid a partial government shutdown at the end of this week, and disagreements over how much money to provide for border security are the primary holdup. Trump has suggested he won’t sign a spending bill that includes less than $5 billion tabbed for building a wall along the southern border, significantly more than the $1.6 billion agreed to in a bipartisan Senate proposal.

While Trump has agreed to consider punting the shutdown deadline in light of former President George H.W. Bush’s death over the weekend, he made no indication of that in his tweet on Monday.

While the president did not elaborate on his claim that erecting a border wall would result in savings for the country, he vowed that “either way, people will NOT be allowed into our Country illegally,” threatening in a tweet that “we will close the entire Southern Border if necessary.”

The president has in recent weeks dangled the threat of shutting down the border as groups of asylum-seeking migrants traveled from Central America with the aim of coming to the U.S. Though seeking asylum at a U.S. port of entry is legal, Trump sought to block those caught crossing the border illegally from claiming asylum in an executive order that has since been blocked by a federal court.

In another attempt to prevent the migrant caravans from entering the U.S., Trump deployed thousands of U.S. troops to the border to fortify security there. The two sides clashed last weekend, with U.S. authorities using tear gas on those they say attacked border patrol agents and rushed the border.

In Trump’s tweet on Monday, he also issued a broad call to “STOP THE DRUGS,” a goal that took a significant step forward over the weekend when Chinese President Xi Jinping agreed at Trump’s urging to classify the synthetic opioid fentanyl as a controlled substance — paving the way for harsher penalties for distributors and a move that could restrict its flow into the U.S.