"If you do more, I'm here to say on behalf of the president of the United States and the American people, we'll do more," Pence said as he opened a conference at the State Department.
Pence thanked President Juan Orlando Hernandez of Honduras, President Jimmy Morales of Guatemala and Vice President Oscar Ortiz of El Salvador for having made progress since they met for the first time last year in Miami.
But he said that over the last year alone more than 225,000 people from the three Central American countries had attempted to illegally enter the United States, accounting for more than half of all illegal immigrants apprehended at the southern border.
He said while the number of arrests from El Salvador has declined, the flows from Honduras and Guatemala are up 61 percent and 75 percent, respectively.
Pence told the three leaders that the best way forward for them is to strength bonds with the United States "even as countries like China tries to expand their influence in the region."
Washington recalled its diplomatic envoys last month from El Salvador, Panama and the Dominican Republic after those countries cut ties with Taiwan to open diplomatic relations with China.
Hernandez replied he would like more certainty about what to expect from the United States, because the funds requested by the Trump administration are less than the money allocated in previous years.
The Trump administration proposed $460 million in assistance last year, 30 percent less than what Congress approved in 2016 under President Barack Obama.
The U.S. has committed more than $2.6 billion in foreign assistance over fiscal years 2015 to 2018 in Central America. The local governments have budgets totaling $8.6 billion from 2016 to 2018.
Hernandez and the other leaders also expressed concern over the Trump administration policy to separate immigrant families at the border.
The two-day Conference On Prosperity And Security In Central America, co-hosted by Mexico, will focus on security on Friday.
Reach Luis Alonso Lugo at http://www.twitter.com/luisalonsolugo
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