Former President Donald Trump on Saturday said he understands the impetus behind a new Republican bill that would block security and military assistance to Ukraine until the U.S. southern border is secured -- while contrasting the state of the border when he left office to how it is now.

Trump was asked on "Fox & Friends" about a new bill introduced by Rep. Matt Rosendale, R-Mont., that would prohibit the expenditure or obligation of military and security assistance to Kyiv until there is "operation control" of the U.S.-Mexico border. It comes as attention in Washington D.C. is increasingly turning to the Russia-Ukraine crisis, where officials believe a Russian invasion may be imminent, but also as the crisis at the southern border moves into its second year.

REP. ROSENDALE INTRODUCES BILL TO BLOCK MILITARY ASSISTANCE TO UKRAINE UNTIL US BORDER IS SECURED

"I certainly understand how people feel," Trump said. "We had the strongest border we've ever had, our southern border. We were three weeks away from finishing the wall after going through two and a half years of lawsuits with the Democrats and winning them all."

"We had the best numbers in the history of our country on the southern border, very little was coming in, very few people were coming in, other than coming in legally, we had the best drug numbers in 32 years, and they were getting much better rapidly -- and all of a sudden this guy takes over, and the border is open," he said, referring to President Biden.

"We’re like a dumping ground, so I can certainly understand how people feel when they say let's try and tie one to the other," he said. "We fight for other people’s borders, but we don't fight for our own border."

It was a sentiment echoed by Rosendale when he spoke to Fox News ahead of his bill’s introduction.

"I think it's quite hypocritical if someone in the U.S. Congress is willing to expend funds to secure a border overseas thousands of miles away while they're not willing to secure our own border," Rosendale told Fox News Digital in an interview. "And we are witnessing not a threat, but we are witnessing an absolute invasion that is taking place right now."

DEMOCRATS' UKRAINE BILL TOUTS ‘INVIOLABILITY OF BORDERS,' WHILE PARTY IGNORES US BORDER CRISIS 

Rosendale’s bill would hold funds back until the border wall system, which was halted by the Biden administration, is completed, and "operational control" as defined by the 2006 Secure Fence Act is achieved. The wall system is defined as a 30-foot-high steel bollard barrier, with all-weather access and patrol roads, perimeter lighting, cameras and detection tech.

There were approximately 1.7 million migrant encounters in FY 2021, and more than 178,800 in December alone. The Biden administration has put the crisis down to a combination of "root causes" in Central America and the Trump administration’s ending of legal asylum pathways.

Republicans, though, have laid the blame at the feet of the Biden administration for having rolled back Trump-era policies like the "Remain-in-Mexico" policy which kept migrants in Mexico for their hearings. The Biden administration ended the policy but has recently been forced to re-establish it under a court order.

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"We had the ‘Stay in Mexico’ policy, now it's called ‘Stay in the United States,’ -- whoever you are, just come on it," Trump said, before going back to the legislation. 

"No, it's a very terrible thing and I must tell you I do understand how they feel when we’re fighting for other countries, but we’re not fighting for our own."