President Donald Trump will sign a proclamation today authorizing a National Guard deployment on the southern border, his Homeland Security secretary says.

The deployment is to begin 'immediately' and has no definite end.

It is also unknown how many guardsmen will be deployed, with Trump's DHS chief Kirstjen Nielsen saying this afternoon that the size and scope of the mission is still under discussion with border state governors.

'It will be strong,' she pledged at a White House news conference. 'It will be as many as needed to fill the gaps that we have today.'

Administration officials characterized the deployment that Trump foreshadowed on Tuesday as a response to the 'growing threat' of illegal immigration that recent border traffic will prove must be handled with 'urgency.'

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President Donald Trump will sign a proclamation today authorizing a National Guard deployment on the southern border

The deployment follows Trump's claim yesterday that he planned to send the military to the southern border until the wall he says must be built can be constructed.

'Until we can have a wall and proper security we're going to be guarding our border with the military,' Trump had said at a meeting with Baltic state leaders. 'That's a big step.'

Congress has been in no hurry to provide him with the funds the project would require, but senior officials said Wednesday that they expect lawmakers' calculus to change as spring shifts to summer.

That's the when highest amount of illegal immigrants enter the U.S. through Mexico.

Nielsen said that historical trend is the basis for the imminent action that's taking place while Congress is on break. In the warmer months north of the border, the number of unlawful immigrants crossing increases, she noted.

The cabinet secretary admitted that border crossings had dropped 'precipitously' since Trump took office, because of his tough immigration rhetoric.

Officials and Trump were warning this week that the threat that on the rise once again, however, because of what they described as weak immigration laws.

An official claimed Wednesday that the number of illegal crossings had been on the rise 'over the last few months and that an even larger influx is expected this summer based on the historical data.

The official said that as of yet unreleased March border crossing numbers will reflect a 'staggering increase from last year' of illegal crossing that will justify the deployment.

The White House is demanding that Congress deliver the money that Trump wants for the construction of a border wall and pass legislation giving immigration officials greater authority to deport people who enter the country unlawfully.

In the meantime, the federal government, working in conjunction with the states, plans to send guardsman to Texas, New Mexico, Arizona and California to assist border patrol with their responsibilities.

The deployment is to begin 'immediately' and has no definite end. It is also unknown how many guardsmen will be deployed, with Trump's DHS chief Kirstjen Nielsen saying this afternoon that the size and scope of the mission is still under discussion with border state governors

Members of the 200th Red Horse Air National Guard Civil Engineering Squadron work on building a road at the border in Nogales, Arizona in this 2008 photo. President Trump says he wants to use the military to secure the U.S.-Mexico border until his promised border wall is built

In this June 13, 2006, photo, Utah National Guard soldiers work on extending a border fence in San Luis, Arizona

Nielsen offered only a vague description on the soldiers' responsibilities, including counternarcotics operations and infrastructure development, while indicating that deployment would be similar to one authorized a little more than a decade ago by former Republican president George W. Bush.

Officials on a call after the announcement said the Department of Defense is working with the White House to identify the tasks that need to be completed and determine the necessary man power.

Trump alluded to the the announcement this morning, saying in a tweet that he'd be taking 'strong action today' after claiming on two occasions yesterday that he was sending the military in.

'Our Border Laws are very weak while those of Mexico & Canada are very strong,' the president today said. 'Congress must change these Obama era, and other, laws NOW! The Democrats stand in our way - they want people to pour into our country unchecked....CRIME!'

He added without further comment, 'We will be taking strong action today.'

Trump did not personally provide any details on the military deployment he envisions such as how many troops he anticipates and from what branch or branches, and the White House had to clarify yesterday evening he was referring to the National Guard when he talked about the troops.

The White House indicated on Tuesday evening that Trump was referring to a mobilization of the National Guard but has offered no additional details

U.S. law may have prohibited the deployment of active duty armed personnel to carry out domestic law enforcement functions, though.

The last two presidents have utilized the National Guard at the southern border, providing Trump with a legal precedent to command reserve troops into service.

Trump's sudden decision to deploy troops seems to have been incited caravan of 1,200 migrants from Honduras that were making their way through Mexico. On Tuesday Trump also threatened to cut off aid to Central America unless Mexican authorities disbanded it.

Upon hearing that the caravan was being broken up later in the day, Trump not only took credit for it, warning that it would have been an impediment to the trade negotiations that the U.S. is currently engaged in with Mexico, he brought up his plan to send in the troops.

'We are preparing for the military to secure our border,' he later affirmed. 'We have a meeting on it in a little while with General Mattis and everybody.'

On Tuesday morning, Trump said the caravan 'had better be stopped' or he'd punish Honduras and other countries that 'allow this to happen.'

'Cash cow NAFTA is in play,' he warned in a tweet. 'Congress MUST ACT NOW!'

He said later that he found the entire situation 'sad' and as he railed against America's 'very bad' border laws, which he blamed on congressional Democrats.

'We have immigration laws that are laughed at by everybody,' he harped at the meeting with Secretary of Defense James Mattis.

The caravan in question split in two on Monday evening, with a portion of the migrants taking a train to Veracruz. The bulk of the caravan was held up by Mexican authorities in Matias Romero Avendano, where travelers were registered and assessed, according to the Washington Post.

Travelers who do not fit the criteria to receive a humanitarian visa will have to leave Mexico. The country's immigration services said they would disband the rest of the caravan by today.

Trump said Tuesday that he directed Mexico to break up the caravan because their immigration laws are stronger than the United States' at present.

'They did it because, frankly, I said, “You really have to do it," ' Trump asserted during his meeting with Baltic leaders on Tuesday, bringing up the North American Free Trade Agreement. 'We’re going to have to include security in NAFTA.'

On Tuesday evening, as experts weighed in to say that the Posse Comitatus Act would get in the way of Trump's planned military deployment, the White House sent out a statement describing it as a National Guard mobilization.

A statement from press secretary Sarah Sanders said the president had been briefed by members of his national security team last week on the influx of drugs and illegal immigrants coming over the the United Sates' southern border.

'Today, he received a follow up briefing to discuss his administration’s strategy, which includes the mobilization of the National Guard,' Sanders said. 'President Trump and senior officials present also agreed on the need to pressure Congress to urgently pass legislation to close legal loopholes exploited by criminal trafficking, narco-terrorist and smuggling organizations.'

A National Guard presence on the border is not unprecedented. Former President Barack Obama deployed 1,200 guardsmen to the same location in 2010 to disrupt the flow of illegal weapons and cash into Mexico. Bush put 6,000 troops there in 2006 to support Border Patrol as part of 'Operation Jump Start.'

Bush's troops were not on the border to act as law enforcement, however, which is what Trump suggested he'd do with his deployment. They assisted border patrol agencies with administrative tasks and gathered intelligence.

They also helped with civil engineering projects, inspiring another Trump idea, perhaps, to have the military shoulder the burden of his border wall.

The president suggested last month that the Pentagon could pay for the structure.

It's not clear how that would work, either, given that the military's funds are appropriated by Congress, and the White House has not offered additional details on how such a plan would work.

In any case, Democratic Sens. Jack Reed and Dick Durbin said Monday in a letter to Mattis that the Pentagon 'has no legal authority' to repurpose federal funds, throwing cold water on Trump's latest border wall plan.

A Central American migrant from Honduras wears his nation's flag during the annual Migrant Stations of the Cross caravan as the group makes a few-days stop in Matias Romero, Oaxaca state, Mexico on Monday

Trump's administration now says it wants to close additional 'loopholes' that allow the unaccompanied minors to stay indefinitely in the United States in a bid to cut down on the number of central American migrants flooding the southern border

Arizona Democratic Rep. Ruben Gallego separately said the deployment is a 'waste' of taxpayer dollars.

'Using the National Guard to do border security is very expensive. For what it would cost the Guard to make just TWO arrests at the border, we could give a homeless veteran permanent housing for an entire year,' he tweeted.

Astrid Dominguez, director of the American Civil Liberties Union's Border Rights Center, said in a statement that the deployment was 'dangerous' and run contrary to 'the fundamental norms of a civil society.'

'President Trump is trying to create a crisis where there is none,' she said. 'This is another impulsive reaction to not getting his way on his border wall, and a maneuver to distract the American public from the crisis he created when he ended DACA for 800,000 young immigrants, whose lives and futures are at risk.'

Trump's pledge to deploy troops and possibly choke off funding to countries that the U.S. assists with drug and crime prevention as a deterrent to such migration upped the ante in Trump's war on illegal immigration a week before he's set to face the presidents of Mexico, Honduras, El Salvador and Guatemala at a South American summit.

He was meeting at the White House with leaders from Estonia, Latvia and Lithuania on Tuesday when he went on a tirade about the caravan and previewed the National Guard deployment.

President Trump debuted his hard-charging position on Easter Sunday in tweets renouncing his support for the Deferred Action for Childhood Arrivals program that gives certain illegal immigrant youth from Mexico legal status.

He continued his assault on Monday, tying the caravan making its way through Mexico to the policy and demanding action from U.S. lawmakers who have continually refused to acquiesce to his plan for better border security.

The White House argued on his behalf that the DACA protections for illegal immigrant youth who came to the United States after a certain date are a 'magnet' for unaccompanied children flooding the southern border.

Senior administration officials said that smugglers are using the program as a way to rope in new travelers. They also cautioned that children coming across the border are likely to request amnesty in a decade the same the way that DACA recipients are now, creating an endless cycle of illegal immigration.

Trump was once supportive of the DACA protections, urging Congress to codify the Barack Obama program his Department of Justice ended on constitutional grounds.

The Republican president said legislators should show 'great heart' for the young people who were brought to America from other countries.

He had almost totally changed his tune on Monday following a long weekend with his top policy adviser, Stephen Miller, an immigration hardliner. By Tuesday the president was taking his demands even further and threatening to end nearly $1 billion in aid to struggling countries in Central America.

Trump said Tuesday that the caravan 'had better be stopped' or he'd punish Honduras and other countries that 'allow this to happen'

Last year, Trump ended a program put in place by his predecessor that gave Central American minors temporary legal residence in the country if they had a parent living in the U.S. legally.

Trump's administration now says it wants to close additional 'loopholes' that allow the unaccompanied minors to stay indefinitely in the United States, in addition to to a request to seal-up the border with a wall.

Officials also demanded an end to the government's 'catch-and-release' program that places illegal children from Central America into the temporary custody of relatives until their day in court arrives, which often takes years, and many do not appear.

On a call with reporters on Monday afternoon, a senior Trump official claimed a spike in the number of unaccompanied minors was the driver, although U.S. Customs and Border Protection data from the current fiscal year shows a jump in November and December followed by a decline in the cruel winter months of January and February.

A total of 136,201 individuals have been apprehended since the Oct. 1 start of the fiscal year, CBP data shows, and 17,575 of them were children.

In all but one month of fiscal year 2017 the year-over-year number of total apprehensions at the southwest border were also lower than in 2016, showing a slow-down in the number of illegal immigrants trying to the enter the country since a 2013 surge prompted government action.

That was the year after Obama introduced his DACA program for Mexican children who were residing in the U.S. and had arrived before the age of 16.

The White House singled out the program on Monday as a pull factor for illegal immigrants from Central American countries like Honduras and resolved that it should be permanently discontinued.

Central American migrants gather before continuing their journey to the U.S. despite President Trump's vow to stamp out illegal immigration. The group is pictured above in Ixtepec, Oaxaca on March 30

Obama's response to the 2013 wave had been to double U.S. aid to Honduras, Guatemala and El Salvador, giving the three countries $750 million to tackle the drug and crime problems that were causing the country's citizens to leave in the first place. The money also funded a campaign explaining U.S. immigration law to Central Americans.

The Trump White House said Monday that existing policy is not and has not been enough. Without a strong deterrent, it said, the children and families from Central America will keep coming to the U.S.

'We don't want to create a humanitarian crisis, and create endless waves of new illegal immigration,' one official told reporters. 'If you're gonna do it, it should be the last time you're ever gonna have to do it.'

Earlier on Monday, Trump tore into Mexico, claiming it had 'absolute power' to prevent the highly-publicized caravan of Latin American immigrants headed towards the countries' joint border from illegally cross into the United States.

'They must stop them at their Northern Border, which they can do because their border laws work, not allow them to pass through into our country, which has no effective border laws,' Trump proclaimed.

The organization behind the caravan, Pueblo Sin Fronteras, or People Without Borders, fired back that 'Trump is trying to turn Central American refugees and other immigrant communities against each other, and use them as a bargaining chip with Mexico.'

'In the face of this bullying and these threats of mass violence, we continue to stand in solidarity with displaced people of all races, ethnicities, creeds, abilities, and gender and sexual identities,' the organization said.

The group of more than 1,000 mostly Honduran refugees plans to cross into the U.S. and demand asylum. They are pictured above on March 30 in the Mexican state of Oaxaca

The group has been making the journey on foot, by bus and on trains. They plan to reach the state of Puebla by April 5, where they will take a four day break in their journey

The long march: The group mostly started from Tapachula on March 25th and his inched their way up towards Mexico City. They will spend most of this week camped at Puebla

Assaulting his opposition in the U.S. legislature, Trump also said: 'Congress must immediately pass Border Legislation, use Nuclear Option if necessary, to stop the massive inflow of Drugs and People.

'Border Patrol Agents (and ICE) are GREAT, but the weak Dem laws don’t allow them to do their job. Act now Congress, our country is being stolen!'

Trump went on to call America's border laws 'pathetic' compared to Mexico's in the Twitter rant that invoked a trade agreement between the two countries and Canada that's being renegotiated on his orders.

He argued that Mexico is 'making a fortune' on the North American Free Trade Agreement.

'With all of the money they make from the U.S., hopefully they will stop people from coming through their country and into ours, at least until Congress changes our immigration laws!' he said.

Another tweet tied the ordeal to an amnesty program in the United States for illegal immigrant children who were brought across the border from Mexico that Trump has pledged to end unless lawmakers give in to his border security demands.

'DACA is dead because the Democrats didn't care or act, and now everyone wants to get into the DACA bandwagon... No longer works,' he said. 'Must build Wall and secure out borders with proper Border legislation. Democrats want No Borders, hence drugs and crime!'

Trump implied in the tweet that he was permanently killing off the Deferred Action for Childhood Arrivals program.

DACA protections do not extend to anyone who arrives in the U.S. after 2007, and recipients must also be under the age of 31. It's currently in limbo after the president's Department of Justice deemed it unconstitutional.

Trump gave Congress six months to make the Barack Obama program law, then proceeded to turn down every immigration deal with bipartisan support that came to him.

In addition to the $25 billion he wants in funding he wants for his border wall, Trump says he won't let the illegal immigrants who came to the U.S. while they were minors to stay until Congress gives him the total overhaul of the legal immigration system he's also requested.

Legislation that meets all four pillars of immigration plan has been unable to pass in Congress, and Trump has stood his ground on DACA, blaming Democrats for the program's lapse.

A Twitter rant on the matter on Sunday had the president's critics accusing him of feigning concern for DACA youth.

Democratic Rep. Don Beyer of Virginia said that Trump had been attempting to 'gaslight the country' for months with his claims that he wants to save DACA.

California Democrat Kamala Harris likewise tweeted that Trump and his government doesn't actually want a solution to the Dreamers' plight.

'They want red meat for their base,' she said. 'They want to purge America's history as a nation of immigrants.'

On Easter morning, before he went to church with his family, President Trump lit up Twitter with a declaration that he was no longer in favor of protecting DACA youth because of 'caravans' that are headed toward the United States' southern border.

'Border Patrol Agents are not allowed to properly do their job at the Border because of ridiculous liberal (Democrat) laws like Catch & Release. Getting more dangerous. “Caravans” coming,' he said. 'Republicans must go to Nuclear Option to pass tough laws NOW. NO MORE DACA DEAL!'

Trump wrote a series of tweets Monday morning about the caravan and the country's 'weak' immigration laws

Trump used the news of the caravan to sound the alarm on immigration, hoping Republicans in the Senate would finally 'go Nuclear,' which means killing off the rule that 60 votes are needed to close debate.

Currently, there are 51 Republicans in the Senate, with Vice President Mike Pence available to break a tie in the GOP's favor.

Previously, Democrats, and then Republicans, changed the rules so a simple majority closes debate on judicial nominations, cabinet appointees, and also for Supreme Court justices .But under Senate Majority Leader Mitch McConnell, a Republican, the legislative filibuster, as it's called, has stayed intact.

Even Senate Republicans such as South Carolina's Lindsey Graham and Arizona's Jeff Flake would be likely to oppose immigration reform legislation that does not include protections for illegal immigrants who have lived in the United States as children and know it as home, though, defeating the purpose of Trump's plan to ram through a border bill that fully funds his wall.

President Trump went on a similar Twitter rant on Sunday

In his Easter Sunday tweets Trump blamed Mexico for putting the U.S. in a position where it even needs to build a border barrier.

'Mexico is doing very little, if not NOTHING, at stopping people from flowing into Mexico through their Southern Border, and then into the U.S. They laugh at our dumb immigration laws,' he said. 'They must stop the big drug and people flows, or I will stop their cash cow, NAFTA. NEED WALL!'

Trump said, 'These big flows of people are all trying to take advantage of DACA. They want in on the act!'

It was Attorney General Jeff Sessions who announced the termination in six months of the Obama-era program that allowed immigrants who came to the United States as children, so-called 'Dreamers' to stay in the country in September, however.

DACA has not ended only because the legality of the program is being argued in court.