It is not clear whether Mexico is offering relief supplies, equipment or money. Any such assistance could put President Trump in an awkward spot, since he has insisted that Mexico would pay for a new border wall he promised as a candidate, perhaps through some sort of reimbursement.

“With Mexico being one of the highest crime Nations in the world, we must have THE WALL. Mexico will pay for it through reimbursement/other,” Trump tweeted Sunday.

Any Mexican disaster assistance would be coordinated through the Federal Emergency Management Agency.

“It is common during hurricanes and other significant weather events for the United States to be in close contact with our neighbors and partners in the region to share data and cooperate as needed and appropriate,” the State Department said.

“When the State Department receives a formal offer of assistance from a foreign government, we work with FEMA to determine the best way forward.”

The Houston area has received more than 50 inches of rain over four days, and as much as a third of the city and surrounding county is under water.

Mexican officials have said the country stands ready to repeat the kind of assistance it offered following Hurricane Katrina in 2005. Then, Mexico provided troops, food and medical supplies for residents of New Orleans. Some troops remained in the United States for weeks to provide humanitarian aid.

“The offer for help and collaboration acknowledges a reality,” Francisco de la Torre Galindo, Mexican consul general in Dallas, told the Dallas Morning News. “We live in the same neighborhood.”

The State Department said FEMA must first evaluate whether the U.S. government can cover the need.

“In the event that federal assets are not available to meet a specific request, FEMA works with the State Department to coordinate and evaluate any offers of support from a foreign nation that may assist in meeting that need.”

Trump visited Texas on Tuesday to address the disaster.